So we have at least 4 with the mod and no issues as of yet.

My holes at 2" (really 2.15-2.25 when I measured very carefully-more egg shapped than circular due to the curvature) are probably the largest.....and I don't have any issues. The CAT gives the needed backpressure and is the only limit now to flow....

Great mod from my point of view. To be honest, I am relieved that tjj7ff's issues were unrelated. I couldn't figure out how x caused y....and now I know that x did not cause y....

If you do the mod, please post on your feelings, thoughts, and issues: good and bad. I would like everyone out there to know as much as possible before they do the mod so that they are able to make the most informed decision:

We have:
-video
-users in PA, CA, TN, OR, Toronto (if not now, soon) and FL
-dyno data
-pictures
-tool data (what was used...air gun (me and others) and hand drill (others))

This has been a great, team effort.



JB

 

Sounds like an ingenious project that could work for the 997TT as well - the exhaust design is almost identical. I was going to suggest to anyone doing this that you could snake a larger coolant hose to a shop vac and use it to suck out fragments as you drill - just alternate the drill and the vacuum repeatedly. There is little chance of the metal fragments making it back through the catalysts' honeycomb into the turbine, but metal dust in the cat could cause it to overheat/ignite. The scenario is unlikely but sometimes a light backfire could suck things upstream

 

I have held off on stating such...but I agree. The designs are almost identical. I plan to always have a TT...so in 5 years...I'll get a 997TT and do this mod. Seeing as you have a 997TT, I say go for it and report back...and post a link to this on the 997TT forum. I would pull the tips off first....just me. I like your vacuum idea. My mechanic did that (did not tell me about it) every minute or so...it adds to time, but is cheap insurance..did not know about that before (just checked). So the vacuum thing does work.

JB

 

BTW if anyone is interested I have a friend wanting to make cheaper high quality aftermarket exhaust units if someone wants to lend a stock unit for jigging.

 

The man has my spare for a while...perhaps we will all get a super exhaust out of this project in the end.....at a fair price no less.

JB

 

It would be great if this mod did no more than send a message that 996tt owners cannot justify 5k for an exhaust. If you were dealing with a 130k car, then 5 grand fits the equation a little better. I do understand that if your goal is to build a TT hot rod, then a better flowing exhaust is an absolute must.

For me it's do I want an EP2L or do I want to buy my 16 year old daughter her first car (she's been working all summer to "help" with the purchase).
seeing Chels being excited abut her own car is SLIGHTLY more satisfying than the TT having a little better sound

no f'in brainer

tw

 

I'd caution everyone to start off small with the holes. The Unibit will allow you to do this. FWIW, the 1" holes do make the car louder, so start off small and finish off with what suits you best.

BTW...the UniBit is nice because the tip starts cutting like a pilot drill, but be careful cutting stainless steel...go slow and don't allow the bit to get too hot or it will turn red hot and then you are F@#$$#@.

My $0.02

 

Fully agree with this on several levels. See the video of TT tommy versus my car (1" v 2"). It is not all about HP/Tq. I basically have a muffler bypass....louder (no drone, but not silent either). I like it. Others might not, hence my videos.

As an aside, a good exhaust for a BMW 335i (bi turbo, new about what a used 996TT is....more or less....more recent development costs to cover.....) is
http://www.activeautowerke.com/whatsnew/main.php

1650 with tips! This is just the first one I found via google.com. I am sure there are better and cheaper....just the first hit.

That is what we should be paying WITH tips....or about 1500 without. The BMW site is getting way too much for the BOV btw....

Anyway...try the 1" first....perhaps 1.375"....with the hand drill and tips off. Then, if you are happy and feel like more noise, go for the air tool router thing like mine....

Best of luck everyone. Keep posting!

 

I'm afraid that if I drill the hole to bypass some of the exhaust, it will lead to the inevitable purchase of a Europipe 2 Loud.... I'm just a sound junkie. The first step in the twelve step recovery is to admit that you are a sound junkie.

1. Admit it to the world, you’re a Sound Junkie.
2. Admit it to you’re spouse that you’re a Sound Junkie, and you will sell your soul to get “that sound” to emanate from your car and have command of that sound with your right foot.
3. Explore your inner self and decide which road you will take to achieve your end result.
a. Short Road: Buy a Europipe directly and be done with it. (Skip to step 12 and avoid the senseless expenditure of time and special tools)
b. Long Road: Dink around with the stock exhaust until the desire to have the ultimate sound is so over powering that you will spend the $5086 to have it.
4. Drill small holes in the existing exhaust system.
5. Drill medium holes in the previously drilled existing exhaust system.
6. Drill larger holes in the previously drilled existing exhaust system.
7. Cut open existing exhaust system and remove baffles.
8. Buy used early generation sub-standard exhaust system off ebay and install on your car.
9. Drive and listen to drone until your ears are exhausted and you find yourself avoiding the RPM and load that causes the drone.
10. Loose the adoration for your car because of the experiences from step 9 above.
11. Enlist the help of those around you to help set you on the right path to audio nirvana.
12. Purchase a Europipe Stage 2 Loud and enjoy, enjoy, and enjoy the concert.

www.europipe.be

Since this is a recovery process, you must consider yourself cured when you have reached the pinnacle of Porsche Nirvana. “Europipe, there is no other”

Thanks for reading, just having a little fun with the subject. I am about to take the short road (3a above).

 

you're right about the EP Loud. amazing sound, actually amazing music.

I hardly ever use the stereo in my 911's.
I keep he windows down and enjoy
now if I could only justify the cost of the EP..... HMMMMMM?????
let me see. (scratching head)
Maybe if I never buy another CD??





tw

 

I gotta point out that the 996TT requires much closer tolerances than a front engined car. If it is off 1/4 inch it won't work...there is no wiggle room. So the builder has to put in a bit more effort to get it right,
Also, most other aftermarket exhaust do not have a cat, or two as in our case. The 100 and 200 cell cats are triple the price of most mufflers.
At any rate, I applaud your mod and agree that there is a market for a good $1500 exhaust.

 

Roadsterdoc, I am currently working on a roughly $1500 exhaust with 100 cell cats and 70mm tubing for the 996TT. It's about 4-6 weeks out at this point...I used to be in the automotive aftermarket business in the 80's and I am getting ready to dabble in it again - as a sideline that I enjoy.

 

What are stock cats? 300 cell?

Anyway, I'll throw another "me too" on the pile. I've been keeping my eyes out for used exhausts, because I don't even want to spend $3k on an exhaust, let alone $5k.

I just want a piece of metal that makes a better (no more hairdryer, please), louder sound and frees up some HP. I'm sure it can be done for far, far less than $3k.

Edit: that Maxspeed thing on eBay catches my eye occasionally. What's the sound like? I'd also really just like a muffler.. headers and tips I can live without

Cheers,
Justin

 

The stock exhaust has two 400 cell cats per side. Most performance exhausts have a single 100 cell cat per side - thus the improved spooling and flow, etc...

 

The whole cat thing has me up in the air....AWE uses 300 cell cats and is happy. John D is right, most say 100 on high end things. I am not sure we would see a difference between 200 and 100 for up to stage III, but who knows.

I have seen 100 cell cats that are "good": HKS or German that are described as wholesale for under 1000 per pair...perhaps well under. Even if they are higher (FVD sells upgrade cats...so we can see a retail price...assume retail is 2x cost more or less)....

Don't get me wrong, Stef and his brother are brilliant. The parts in a Jaeger Lecoultre watch or a Rolex submariner are not worth their prices....the latter perhaps to a greater degree.....but people pay. One cannot fault a business for getting what the market percieves as a price. I just feel that the 996tt market has shifted from those who can pay 130k for a car and afford it to be worth half in 3-4 years to those who buy it for half and expect it to be worth 75% in 304 years....60k is not chump change. 1500 for an exhaust is not chump change in the big picture either....5k is just too high for this market in my mind much longer...those people are in 997tt's and such. Or F430's.

JB