# Question for those with with the sport exhaust and the second cat delete in the TTRS



## keitth24 (Dec 5, 2007)

*Question for those with with the sport exhaust and the second cat delete in the TTRS (UPDATE: resonators deleted)*

I'm picking up my TTRS soon and I am reading that some of you guys delete the second CAT in the exhaust! I am wondering if this still allows the car to pass the MOT? Or do you guys need to stick the secondary cat on before emissions testing. THanks!


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## JohnLZ7W (Nov 23, 2003)

keitth24 said:


> I'm picking up my TTRS soon and I am reading that some of you guys delete the second CAT in the exhaust! I am wondering if this still allows the car to pass the MOT? Or do you guys need to stick the secondary cat on before emissions testing. THanks!


 You won't get a CEL so if all they do is scan for codes then no problem. If they do a visual inspection then they might notice the fact that your cats are missing.


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## - Jeremy - (Feb 23, 2006)

Yeah, and the plate that's welded onto the pipes that says "NOT FOR ROAD USE" or something like that. But without looking at it, they won't know at all. The measurement occurs between the first and second cats. 

- Jeremy -


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## keitth24 (Dec 5, 2007)

Thanks for the quick replies! Was the install easy as just removing the secondary cat and fitting the test pipe? Or was there some welding involved?? How does it sound afterwards; was it worth it?:laugh:


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## JohnLZ7W (Nov 23, 2003)

keitth24 said:


> Thanks for the quick replies! Was the install easy as just removing the secondary cat and fitting the test pipe? Or was there some welding involved?? How does it sound afterwards; was it worth it?:laugh:


 No welding required, I think it's about 10 13mm bolts total to do the swap. Absolutely worth it, should be required mod


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## keitth24 (Dec 5, 2007)

Also, are there any resonators in the stock sport exhaust?


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## JohnLZ7W (Nov 23, 2003)

Yep, same exact setup as the standard exhaust. Sport is on the left here


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## twin__turbo (Apr 12, 2012)

I am curious about the sound difference too.


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## mageus (Sep 1, 2004)

If you're in a state with visual inspection (e.g. CA), you'll need to swap the stock ones back in. 

Once you replace the stock bolts with the through bolts during the install, it literally takes 5-10" to swap out, not including the time to jack-up and jack-down. No big deal to do this once every 2 years. 

There are 6 bolts to remove on the front, and 4 bolts to loosen at the back. A tip - during the installation reorient the nuts so your ratcheting wrench has good clearance. It'll be obvious when you do the install.


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## keitth24 (Dec 5, 2007)

So is the usually mod to just remove the secondary cats, or are the resonators taken out too?


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## - Jeremy - (Feb 23, 2006)

keitth24 said:


> So is the usually mod to just remove the secondary cats, or are the resonators taken out too?


 The usual mod is only the secondary cats because it's very easy to do. Removing the resonators requires some cutting and welding of the exhaust. Honestly, deleting the secondary cats with the sport exhaust sounds really good. It's more raw than stock and probably 20% louder, maybe. It gives some nice burbles and pops when shifting it at redline or puttering around town. It's not perfect, but it's only $200 for the pipes so it's not going to be as good as a $3000 Ti exhaust or something  

- Jeremy -


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## keitth24 (Dec 5, 2007)

that sounds great. Now just gotta wait for the car! I currently have a 2001 225 and I deleted the resonator on my aftermarket catback, which required welding, but it got significantly louder too and droned a lot more. I'm just wondering if anyone here has any experience with that with the TTRS


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## - Jeremy - (Feb 23, 2006)

keitth24 said:


> that sounds great. Now just gotta wait for the car! I currently have a 2001 225 and I deleted the resonator on my aftermarket catback, which required welding, but it got significantly louder too and droned a lot more. I'm just wondering if anyone here has any experience with that with the TTRS


 Yeah, it does drone around 2k but the exhaust has a flapper valve that keeps it pretty quiet under 3k. So you won't be bothered by drone unless you're in sport mode which opens up the flapper. Or unless you do the flapper mod which will really surprise you (and your neighbors) with how loud it is in the morning on a cold start  

- Jeremy -


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## Marty (Jul 14, 2000)

- Jeremy - said:


> The usual mod is only the secondary cats because it's very easy to do. Removing the resonators requires some cutting and welding of the exhaust. Honestly, deleting the secondary cats with the sport exhaust sounds really good. It's more raw than stock and probably 20% louder, maybe. It gives some nice burbles and pops when shifting it at redline or puttering around town. It's not perfect, but it's only $200 for the pipes so it's not going to be as good as a $3000 Ti exhaust or something
> 
> - Jeremy -


 And pollutes continuously for a little more noise. Huge thumbs down.:thumbdown:


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## mageus (Sep 1, 2004)

Aah, the Marty and Jeremy debates return! 

The 2nd cat delete doesn't make it much louder, but adds more fidelity and depth to the sound. Kinda like a nice stereo reproduces the highs so well. You get all those pops and crackles. When _up_shifting from 1st to second there's this short grunt/burst. Great bang for the buck.


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## Dan.S (Jan 3, 2012)

Marty said:


> And pollutes continuously for a little more noise. Huge thumbs down.:thumbdown:


 GO hug a tree, and leave the automotive enthusiests that like it here. Most retarded comment I have ever seen on an auto forum, period.


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## DrDomm (Feb 16, 2003)

mageus said:


> If you're in a state with visual inspection (e.g. CA), you'll need to swap the stock ones back in.


 You think the "inspector" knows that your car has additional cats, beside the primary one (I'm not sure how CA does their inspections)? 

BTW, I removed the "off road" tags.

Glad to see Marty is still defending our planet.


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## keitth24 (Dec 5, 2007)

Just bringing this thread back to life as I ordered my mid pipes. So they do not actually actually measure the emissions coming out of your tail pipes???


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## YYC Dubber (Jun 23, 2011)

will be interesting if anyone opts for the APR Downpipe, APR splitter adaptor attaching to Milltek/ 034 Moto secondary cat delete straight pipes thru to the sport exhaust.... 

dont mind the drone at all, will be interesting to hear this combo since the Sport OEM exhaust note is hard to beat


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## DrDomm (Feb 16, 2003)

keitth24 said:


> Just bringing this thread back to life as I ordered my mid pipes. So they do not actually actually measure the emissions coming out of your tail pipes???


 Some states (i.e. NY) just make sure there are no error codes/CELs. There are no sensors behind the secondary cats.


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## keitth24 (Dec 5, 2007)

So I finally got the secondary cat delete done!! I went with 034 motorsports. And it sounds Amazing! 
It sounds louder and sharper, not as muffled as before. Great mod and extremely pleased!


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## dbturbo2 (Oct 22, 2008)

Keitth, is that with the factory sports exhaust?


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## Optimus812 (May 5, 2012)

This mod sounds so tempting.. I just picked up my RS a couple of days ago. Could always use a little more exhaust sound volume


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## keitth24 (Dec 5, 2007)

Yea I went with the factory sports exhaust and every time I open it up, it puts a smile to my face.

My previous car was an 2001 Audi TT 225 with a full custom turbo back with a 3 inch down pipe, high flow cats, no resonators. That car was super loud and drony, with lots of cracks, bubbles and pops. TBH, I loved that sound and I thought that the factory exhaust with the straight pipe in the Audi TTRS would not be enough, but it still satisfies the sound requirements that I like, albiet its not as loud as before, its still a sensational sound.

If anyone with the sports exhaust has any doubts about the mid pipe modification, I hope that convinced you!:laugh:


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## keitth24 (Dec 5, 2007)

I remember reading in this forum a zip tie modification that can be done to keep the valve open all the time. I tried a search but I cannot find that picture/thread with the mod. Can someone point me in the right direction.


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## keitth24 (Dec 5, 2007)

never mind found it!


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## InTTruder (Mar 28, 2006)

See my thread about the APR Stage 2 + RSC package on my car-


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## keitth24 (Dec 5, 2007)

Ok so a month ago I had my secondary cats removed and the sound improved a lot!!! The sound was less muffled and was sharper. Today I had the resonators removed and I'm here to report the sound changes. 
1. The exhaust got even louder!  
2. The noise became harsher and not as smooth as before 
3. The exhaust bubbles and pops a lot more 
4. The car sounds great at higher rpm but at low rpm, It got slightly raspier.. 

So it's a give or take situation. For me, I thought it was great mod since it was so cheap to do and I think it sounds great! I don't think there is too much drone over just having the secondary cats removed.


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## - Jeremy - (Feb 23, 2006)

keitth24 said:


> Ok so a month ago I had my secondary cats removed and the sound improved a lot!!! The sound was less muffled and was sharper. Today I had the resonators removed and I'm here to report the sound changes.
> 1. The exhaust got even louder!
> 2. The noise became harsher and not as smooth as before
> 3. The exhaust bubbles and pops a lot more
> ...


 I've been wanting to do this but haven't heard any examples yet. I would be very grateful if you could make a video and upload it to YouTube. It's pretty easy to do. 

- Jeremy -


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## keitth24 (Dec 5, 2007)

I can do that for you when the weather gets better...it's been raining here the past few days!


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## 996cab (Aug 13, 2011)

keitth24 said:


> ... Today I had the resonators removed and I'm here to report the sound changes.
> 1. The exhaust got even louder!
> 2. The noise became harsher and not as smooth as before
> 3. The exhaust bubbles and pops a lot more
> ...


 I did this mod last year and it was the best mod to hear the 5-pot properly...past 2k RPM the note build up is like a powerboat...beyound 4k RPM I get that raspy note you mention and the pops and thunder on gearchange...all this is done using OEM DP; MillTek catless middle pipes and also MillTek 'y' pipes which loses the two rear resonators. My back box is OEM Sports...I luv the note so much that I cancelled the TUBI custom system that I was having made...cancellation fee was a touch harsh however...!


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## keitth24 (Dec 5, 2007)

I'm still waiting for the weather to clear up so I can a vid for Jeremy....the engine sounds amazing!!! It seem you can hear everything unrestricted instead or just what Audi wanted you to hear...I guess some ppl might find it too much but the car sounds waaaay more badass


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## 996cab (Aug 13, 2011)

For Jeremy, FFWD to 1:48 - http://www.youtube.com/watch?v=aF_PApI2rNQ - you can hear the pop at 1:56...

http://www.youtube.com/watch?v=isRYzMFDSsk


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## keitth24 (Dec 5, 2007)

Those are great videos!! Pretty much what my car sounds like...the biggest difference is that the car seems more "boomy"....I'm thoroughly enjoying it...


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## dbturbo2 (Oct 22, 2008)

Keitth, regarding the overall loudness of the sport exhaust with the cat delete, how does it compare to the sport exhaust with flapper mod at startup?


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## keitth24 (Dec 5, 2007)

1. Stock sport exhaust with flapper mod at startup is moderately loud while it swarming up. It sounds muffled but it's nice for those that want something sporty but not too loud

2. Stock sport exhaust with secondary cats delete with flapper at startup is louder! The sound is not muffled and it's sharper. It's a great sound.

3. Stock sport exhaust with secondary cats delete, resonator delete with flapper mod at startup is insane! It sounds like number 2. But it's even louder and it bubbles a little more. It seems to echo more for some reason.


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## - Jeremy - (Feb 23, 2006)

996cab said:


> For Jeremy, FFWD to 1:48 - http://www.youtube.com/watch?v=aF_PApI2rNQ - you can hear the pop at 1:56...
> 
> http://www.youtube.com/watch?v=isRYzMFDSsk


Thanks, William! Is your car still set up like this? Hopefully I'll get to hear it at the 'Ring on the 30th.

- Jeremy -


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## 996cab (Aug 13, 2011)

keitth24 said:


> Those are great videos!! Pretty much what my car sounds like...the biggest difference is that the car seems more "boomy"....I'm thoroughly enjoying it...


 Yep, the engine sounds great when moving at pace...


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## R-power (Jan 9, 2008)

keitth24 said:


> Ok so a month ago I had my secondary cats removed and the sound improved a lot!!! The sound was less muffled and was sharper. Today I had the resonators removed and I'm here to report the sound changes.
> 1. The exhaust got even louder!
> 2. The noise became harsher and not as smooth as before
> 3. The exhaust bubbles and pops a lot more
> ...





996cab said:


> I did this mod last year and it was the best mod to hear the 5-pot properly...past 2k RPM the note build up is like a powerboat...beyound 4k RPM I get that raspy note you mention and the pops and thunder on gearchange...all this is done using OEM DP; MillTek catless middle pipes and also MillTek 'y' pipes which loses the two rear resonators. My back box is OEM Sports...I luv the note so much that I cancelled the TUBI custom system that I was having made...cancellation fee was a touch harsh however...!


dear all,
mainly Keitth24 and 996cab
sorry to jump in again in this brilliant topic,
but

ivo from como lake-italy
with TTRS my12 stronic OEM exhaust sound.
here my history

i've removed sec.kat with milltek bypass
sound fantastic (also 180 laps in nordschleife helps)
my actual sound is this, only with miltek bypass and sport OEM exhaust by audi with left valve in OPEN mode





I'm wondering about to skip Resonator....
but 

My idea (and let me know if this can work or what is your proposal):
i wanna to open the last part of the exhaust and *let be the right silenced part simmetrical to the left one.*
here a friend OEM exhaust just opened not modified.









what do you think about ??
can it work? the sound can nearly double ??
or what can be the best solution to increase volume without changing note ??

thx in advance for your support,
ivo


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## JohnLZ7W (Nov 23, 2003)

My car with stock primary cat, milltek secondary cat deletes, center resonator delete, sport exhaust with valve open. The mic is placed near the left exhaust tip. Resonator delete changes the tone a bit, definitely makes it louder and a bit more raw. It's a cross between the sport exhaust and Borla (which I also ran for awhile).


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## ZPrime (Mar 7, 2006)

R-power said:


> dear all,
> [stuff removed]
> 
> My idea (and let me know if this can work or what is your proposal):
> ...


That's the first time I've ever seen the OEM backbox opened up, and it's interesting. Is this the "stock" (not "Sport") exhaust? 

Notice how the right section apparently has no connection to the upstream pipe. I assume that muffler was filled with fiberglass matting and it was removed before the photo?

The right section being not directly connected is what makes it so quiet. Since the left side is actually piped through the "suitcase" and directly out the side, that's why it gets a lot louder when the flapper is open -- the sound isn't being muffled much at all through the suitcase, since it's contained within that pipe.

Has anyone ever cut open the Sport exhaust to see how that backbox is different? I have both (car came with the quiet / non-sport and I bought a used Sport catback from another member), but I don't want to cut open the Sport piece since that's what I have installed on the car now.


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## ZPrime (Mar 7, 2006)

JohnLZ7W said:


> My car with stock primary cat, milltek secondary cat deletes, center resonator delete, sport exhaust with valve open. The mic is placed near the left exhaust tip. Resonator delete changes the tone a bit, definitely makes it louder and a bit more raw. It's a cross between the sport exhaust and Borla (which I also ran for awhile).


What did you use for the data gathering / overlay there? That's really slick with the TTRS-ish gauges and everything. Harry's Laptimer? Or something more advanced?


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## R-power (Jan 9, 2008)

thx to 996cab 
for supporting me in understanding RESONATOR and other stuff.

I ask too what kind of sw is the wonderful overlay on AUDI TTRS here above.

then
here photos of OEM AUDI TTRS "not-sport", opened from a friend





























the ehaust in my tube video is an OEM-sport one,
but as far as per my knowledge the only difference between Normal and Sport is that the valve on sport will open at 2.600rpm and on the normal (if I remember in a good way) 3.400 rpm
No other harware difference IMHO.

Do you know if there are some other differences between NORMAL and SPORT OEM exhaust ??

ciao


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## JohnLZ7W (Nov 23, 2003)

R-power said:


> the ehaust in my tube video is an OEM-sport one,
> but as far as per my knowledge the only difference between Normal and Sport is that the valve on sport will open at 2.600rpm and on the normal (if I remember in a good way) 3.400 rpm
> No other harware difference IMHO.
> 
> ...


There's no difference in valve operation between the sport and normal exhaust. I had a standard exhaust originally with the valve open all of the time and it was definitely different to the sport exhaust with valve open. From your pictures the internal design of the muffler box itself is identical so it seems that the only difference is as we suspected early on and that's the amount of fiberglass packing in each one. Pretty nice profit margins on that for Audi!


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## ZPrime (Mar 7, 2006)

*FV-QR*

Well, we still don't have any pictures of the inside of the Audi Sport backbox, do we? R-Power's pictures above are all from the "normal" piece, if I'm reading correctly. It's possible that the right side design is different, or it could just be less fiberglass... no way to know without cutting one open. 

I'm using mine so not volunteering!


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## R-power (Jan 9, 2008)

Photos are of NORMAL OEM.
I've opened today the right section (that without valve)of my Oem SPORT 
I can confirm u all that is the same of normal one.

We have not opened the left one.
But the technician says that he thinks the left normak is really the same of sport.
He thinks.

I do not need to open and modify the left 
So on this i cannot help.


< sent with my Z3c & tOpatalk >


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## dubbinitmk6 (Oct 26, 2010)

R-Power, is that a modified spoiler support? :what:


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## R-power (Jan 9, 2008)

dubbinitmk6 said:


> R-Power, is that a modified spoiler support? :what:


yes,
it is a full NEW rear wing.
I've "invented" it together with a friend who works in Carbon-Kevlar pieces.
I've this idea since I had my TT-s
Finally i succeeded in end 2014.

Wing it is near 10-15% bigger in all dimensions than OEM one
Support are near 5cm higher then OEM
Incidence (position) of the wing is the same of the OEM one (without a specific scientific study, just placing my car and a OEM wing TTRS side-by-side and defining the angle)

My one is full real carbon matt finish (are mirrors and fuel cover)
You can have also brilliant finish
or cheap fiberglass if u want
the plus is that big-wing is fully working with OEM support and big-Support is fully working with OEM wiing and the big-support work perfectly in OEM holes 

https://www.gm-carbonparts.com
talk with Andrea, do my name IVO-ITALY
we started with 5 pieces,
actually he told me he is arrived to 20pcs, some also in USA and australia
starting from that U tube video

sorry for this advertising
but I think that the benefit of a community of fanatics of one object is to share infos....


*THEN, BACK AGAIN TO EXHAUST.*
I'm in the same situation of Zprime
i bought car with NORMAL, I had an additional normal from Audi as warranty due to an issue to the valve (so totally2 Normal in my garage), then i found a SPORT used one, i've installed (and actually in my car) and I sold the 2 NORMAL.
So neither me want to open the left part of my SPORT to understand how it works.
No one has google images about it ?

I've asked to a friend who works in CAPRISTO factory if there exists an instrument to analyse an exhaust exernally.....
let u know

ciao


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## ZPrime (Mar 7, 2006)

*FV-QR*

molto bene R-power  My sister played ice hockey at World University Games in Trentino 2 years ago - that is all the Italian that I can say.

Very cool that you have a friend doing carbon fiber work. Some people here may be very interested in that link!

The only way to "look inside" a closed exhaust would be ultrasound or a small camera. You can't X-Ray through metal.


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