mbintx

Looking to pick up some HP and improved sound. Seems the cat bypass tends to "advertise" more of a power gain, though others recommend the primary bypass instead. How does a chip affect results with either?
Would doing both add incremental power without things getting too loud?

Once this is figured out, I'll add a Steve Wong chip.

Super90

I'm currently running a cat bypass and a primary bypass. You could also do cat and secondary bypasses. I just received my new Steve Wong chip and have not installed.

I think his chip for the exhaust bypasses is the same regardless of if you are bypassing primary or secondary. Best to call Steve and tell him your intentions. You're in good hands...

mbintx

I just need to listen to your car and mine side-to-side...

Super90

I'll have my chip in soon and some miles on this fresh motor, then we can switch cars.

R.

mooty

the wong chip is biggest bang for the buck in porschedom.
BIG difference for little cost and easily reversible
i run cat and 2ndary bypass

Altex121

I ran a race cat and primary bypass for a long time... always wanted it a little louder, so I threw a J pipe on as well

now the car sounds like a Harley. Would probably switch back if I drove the car more, but I like loud things. Still need a chip

Ken D

https://rennlist.com/forums/964-foru...ml#post9503302

911Jetta

Keep in mind that your exhaust sound (not just noise level) will change depending on which muffler you bypass. I like the sound of bypassing the primary exhaust better... (truer flat six Porsche sound)

I originally had just a primary exhaust bypass (Cup pipe), and it's a great sound and nice weight savings. After years of just the primary bypass, I purchased a used Fabspeed Cat Bypass (no affil) from a Rennlister who was selling his car... WOW, that was the sound I was really looking for. Also, the cat bypass bolted on with no modifications or gaps, perfect fit. It all works great with my Wong chip (93, Primary and Cat pass program).

It a nice deep, heavy breathing mechanical sound. I also hear more valvetrain music since the cat bypass doesn't have a large shield on it like the stock cat does. Yes it's a notch or two louder than just the just a primary exhaust delete, but definitely not too loud. Just sounds very strong, even my non-car loving friends (99% of my friends) love the sound and give it thumbs up.

For the complete package, drill your airbox also.

The Greek

Good feedback here ^

I was going to order a secondary bypass, primary bypass and cat delete/high flow cat and just mix it all around until I find the right setup.

Spyerx

I'll be doing custom tuning on mine, but I have a slightly massaged 3.6 (993 S cams, etc). Will run rothsport headers, into a 991 Turbo S muffler, dual in, dual out. No cats. But software will be custom tuned for this setup. Shop has done a few of these and it sounds tasty.

Vandit

Cup pipe sound is more marque-correct. G-pipe sound is more hot rod.

Fabspeed Motorsport

Personally, I'd recommend going with the Primary Muffler Bypass, Catbypass Pipe and then pair those with a Steve Wong DME Chip.

We typically see ~16whp/14ft-lb gain with just the Catbypass alone, along with a deeper, more aggressive exhaust tone. The Primary Muffler Bypass and Catbypass Pipe gives you that true Porsche flat-6 sound

I agree that the DME Chip is your biggest bang-for-your-buck - you'll see more power/tq but the overall driveability improvements are night and day. Throttle response is greatly improved along with a smoother, more linear powerband. Steve will take into account what modifications you have along with fuel octane etc.

http://www.fabspeed.com/964-carrera-...r-bypass-pipe/

http://www.fabspeed.com/porsche-964-...atbypass-pipe/

http://www.fabspeed.com/porsche-964-...-chip-upgrade/

Please let me know if you have any questions - I'd be happy to set up fellow Rennlisters with forum pricing

- Alec

mystert

I have a cat delete, primary delete, stock secondary, aftermarket tip, and a Steve Wong 91octane chip in my Cabrio and I love it. Not too loud, definitely faster than stock. No complaints. Its easy enough to swap the stock cat back on if you ever have too and I have passed CA emissions with the SW chip and stock cat. Go for it!

toothfixer

I also have the cat bypass, primary muffler bypass and steve wong chip. Im very happy with the sound, it does get loud after a long drive but its manageable. I have read that bypassing the cat and both mufflers would be too loud for street duty

mbintx

Thanks, all!