Indykid

I just spoke to someone about a cat bypass pipe to get a little more hp. Does anyone have this done to there turbo and if so how much hp did you pick up and what draw backs have you encountered?? Any input would be helpful.

thanks

Indy

Jeff 993TT

Have you checked out http://www.993tt.com ???

Coincidentially, I just sold a set of cat bypass pipes on ebay last week.

viperbob

Indykid,

I installed a set of cat bypasses from FVD. They were less than impressive. They cost a lot of money, the car was not noticably louder, and I could not feel much of a performance improvement. Oh, and the good thing was, they are a pain to put on. And I get to go through the experience again each time I need to pass smog.

Try the Fabspeed muffler bypasses first. There are a third the cost, install in 10 minutes, give a sweet sound, takes 60 lbs out of the back of your car, doesn't effect smog, and give much noticable improvement in performance. Can't really beat them...

John H. in DC Area

Bob, can you, or perhaps Old Guy or some other person who has the muffler bypasses post a pic of the back side of one of the rear wheel wells? I'm a stickler for impeccable aesthetics and am deathly afraid of ending up with this look ...






Thanks!

mkhn

John,

What part of the picture are you pointing out that you're afraid of ending up?

ca993twin

John,

If this image is too crappy, I have a higher definition image I can email to you. Let me know.

John H. in DC Area

Mike, Steve, et al., the visible dead space/cavity is what I don't like ...

That's not my car, and I doubt it has the fabspeed muffler bypasses, but that's just an example of a big ugly cavity where the muffler used to be. That car looks like it has 17" wheels, and in fact it looks like a body kit thrown on an older 911 chassis, but it illustrates my point. Just curious to see one of your cars from the same angle. Sorry to be a pest. BTW, gorgeous photo Steve.

ca993twin

John,

Ahhhh. Now I see what you're getting at. I honestly never noticed the gap before, and now that you point it out, it still looks OK to my eyeball... but thats just me. I went to thje garage and snapped this close-up, flash picture of the area in question. o you think it would look better to see the backside of a muffler can in there?

viperbob

hmmm. I don't think I have enough room there to make a picture worthwhile.... Steve still maintains some cleareance there....

Some PSS9s and a proper setup and you will never know that space existed...... Also good for airflow with the turbos...

Carrera GT

There's a few things going on with the car in that pic (where's it from?)
It seems to be a 993 C2 or C2S with a Turbo wing and "Euro" sort of corner markers.
It has no sunroof, which is great and the wipers are set close together, so it's either heavily modified (and nicely done) or it's a 993 or some sort.
The gap behind the rear wheel is the US ride-height mostly and cosmetically not an issue with the "can delete" pipes (in my humble.)

Cheers,

mkhn

I have seen both Bob's and Steve's car in person. With Bob's 11" 996TT rear wheels and lowered ride height you can barely see day light between the tire and rear fender not to mention the space made with the removal of his mufflers. Steve's car was on jack stands in Bob's garage getting a PSS9 makeover and I had the opportunity to stick my head well up into his TT's rear fender well and all I could think was how great that 60-70lbs of "dead" weight was removed and how clean the layout was to the polished tail pipes.

That will be my next mod after my savings recover's from my TT's planned suspension makeover this weekend.

TB993tt

All European tuners will put Race/Sport cats on to lessen back pressure as soon as the boost curve is altered from stock (cat bypasses are presumably even better) With a stock ECU (boost curve) any exhaust mods are likely to be pointless (apart from the sound issue). Before one pays attention to the cats, the first thing to look at is the mufflers. Either buy a proven performance muffler (I don't think the Rennlist vaunted RSRs fall into this category) or the muffler bypasses. A word of warning on the muffler byepass is that if used in conjunction with sport/No cats, the exhaust is VERY loud, so if you intend to mod further than around 450hp you may have to throw/give away the muffler byepasses (I did) since they will be too loud.
FWIW Andial told me a few years back that they maintain stock cats with their 3.8 , 570+hp motors - that definately goes against every other Euro tuner who will change out the cats as the 4th "bolt on".
Also note that whilst the muffler byepasses will be the lightest "muffler" you can fit, the Cargraphic mufflers (made in the UK by race exhaust specialsts Phoenix) are also substantially lighter than stock.

John H. in DC Area

Thanks for your posts and efforts, guys.

Steve, that picture helps alot and I see there's only a very tiny view of the cavity, I'm very pleased with that, mission accomplished.

I just wanted a picture of it so I could weigh the trade-off myself before I jumped in. Your picture confirmed that for a lowered car (and mine sits about as low as yours, Steve, with Eibach springs), there is virtually no aesthetic issue, so then my logic is a lot like Mike's and everyone else's: get that weight out of there, baby! and any benefit in spool-up/low backpressure is just a bonus.

Carrera GT, I agree with your thoughts on that car, as you'll see in my prior post I theorized that it's an older 911 with a 993 body kit.

Read your post TB993TT, if you check my sig you'll see that I already have a very nice $ounding and high performance Cargraphic exhaust, that's why I'm trying to figure out if I want to dump it, keep it and switch back and forth with the bypasses depending upon the noise level, or stay with what I've got.

Thanks for your thoughts everyone.

Enjoy the boost!

TB993tt

John H
I am a little confused here (nothing new there) but I thought I was replying to Indykid's post.
FYI a package for the 993tt which was originally offered by TTP (who did/do the ECUs for Gemballa) was an ECU, sport cat and sport muffler + air filter - in those days they claimed 470hp - note the ECu was specific to the package, but it occurred to me that you basically have this package less the cat mod. Why don't you fire off an email or fax to TTP (www.t-t-p.de) , give them your ECU numbers and see exactly which program you have.
BTW, IMHO the Cargraphic mufflers are the best performing on the market for the 993tt

John H. in DC Area

I no doubt caused the confusion, TB993TT, by hijacking Indykid's thread, my apologies

It's funny that you mention the TTP package, as that's the package that I have, my ECU was tuned by the software guru behind the TTP package (Gunther), and my local shop is a distributor for TTP packages. Not to blow smoke up your *** (unwanted backpressure?), but your knowledge of the TT world and associated mods is incredibly broad, I'm impressed.

I love the way my current exhaust sounds (in fact I like it better than the fabspeed muffler bypass sounds on fabspeed's site), but am soooo tempted by the loss of weight and loss of backpressure. Oh the choices in life!