Hi Folks I have a 2004 996, I picked up a set of muffler by-pass pipers from fab speed and took off the factory mufflers. Now the car is very loud which the neighbors just love on early Sunday mornings. However the car tends to surge a bit, and it’s very smooth anymore and I’m wondering if I gained any performance by putting them on or did I just make it louder? Would an aftermarket set of mufflers be a better choice? The drone is starting to get to me a bit as well.
Thanks

 

You lost low-end power and probable pissed off your neighborhood as well..

 

I did the same thing as you with the bypass pipes. They lasted on my car about 2 weeks before they came off. I noticed the bottom end was lagging, I opted for a set of fab speed mufflers and love them. Nice sound and performance.

 

i had the opposite experience. i put the bypass pipes on and while they were obnoxiously loud, they made for quicker acceleration at any RPM. I think what you're noticing is the amount of noise you're making isnt reflective of your acceleration. with the factory exhaust it doesn't get noisy until you're at WOT or in the higher RPMs

 

I'm running fabspeed headers, straight pipes where the cats used to be, and Fabspeed mufflers. My car is obnoxiously loud too. Don't care much about the low end as I only drive it on the freeways and outside the city, just on the weekends. Sometimes it'll even backfire and scare the **** out of everyone at a crosswalk. Love it!

 

Whats the best way to get back the low end power losss?

 

I hate to be a negative nancy, but I dont think it's supposed to do that.... ever.

I have a 996tt with no cats, no mufflers and my old 996 had no cats and no mufflers. Neither has ever backfired.

 

Yep, yep, and that's why I am sticking to stock exhaust system and would never consider anything that drastically reduce the back pressure, my "Boy-Racer" days are long gone.

 

Cars without smog equipment backfire from the exhaust occasionally. It's not unknown. My 996 will sometimes let out a little backfire if I change gears in the low RPM range, and the headers/straight pipes/mufflers are nice and hot. My RS6 is also completely cat-less and will sometimes backfire if I let off the gas at certain points. But congratulations on neither of your cars every experiencing this phenomenon

 

The best set-up is HJS Hi-flow cats, " hollowed out " mufflers or Porsche TE sport exhaust with switch valve. Put all those aftermarket system to shame. Power comes from custom headers, IPD plenum and a solid tune. Get crazy and retard the cam timing like a GS car

 

If you are loosing performance, try Viagra.

Opps, wrong forum.

:>p

 

That's too bad. Maybe you can reinstall the proper exhaust and get your car back to where it should be. There's nothing attractive about a great looking car that nobody wants to hear coming.