Do any of you who have these experienced and hp gains? Any CEL's? What are the weight savings? Any sound clips?

 

Weight saving is very good -- factory mufflers are around 20-25lb per side.

Noise is generally over the top for street and exceeds noise limits at tracks like Laguna. But it does sound great.

There's no EPA emissions problem and it doesn't effect the sensors around the cats, so it doesn't throw a code or trigger the CEL.

You can make yourself a pair of "bypass" pipes from a single U-bend, just measure and cut it, flare at one end, clamp it and bolt on the factory tips. I did this in an hour or two. After the car was on the road for a few weeks, the owner decided the novelty had been worn away by the dBs. It is loud, especially as rpms climb through resonate frequencies, one of which arises at 60 mph in 5th (a hassle on most freeways...)

In the country and on the track, it's a great, great sound, but you're not really gaining HP. We ran a before/after dyno on removing the mufflers (no measurable delta) and on the air-filter (no gain) so it's just for the amazing sound of having your own Cup car on demand.

I toyed with a simple slide-valve to open up a by-pass on wide-open throttle, but once we found no hp gains on the fixed pipe, the only value would be like the sound effect.


Cheers,

 

Cool, any pics/measurements of your project?

 

some people have also used the Pep-boys 90 degree bend pipes too, that turned out ok...not as finished as Fabspeed's though...but hey $550 vs. $30(at most)

 

I'm sure we did take some dyno run pics and the numbers are still on the computer (we used Vishnu/Shiv) but the rest of the work was just exhaust pieces -- easy to reproduce if someone wanted to DIY their own PSE. The trick would be to find a slide valve instead of a butterfly valve and a durable but light actuator assembly.

I just got a GT3 for myself recently so I have a renewed interest in all things GT3. Right now I'm trying to figure out an exhaust system without paying for brand name products (although the CG cans are very nice) which will probably become a pair of Borla muffs and some short pipes off the factory headers (sans cats.)

Of course there's also a lightweight flywheel, suspension, rotors and pads, control arms, bushings, engine and transmission mounts, aerodynamics and cold air flow to the engine intake etc. Lots of fun projects.

The only real trick is getting track days at Laguna or Sears -- it seems like everyone and their dog signs up for events long before I can figure out my calendar. : )

 

Cool,
Let me know if you want to sell your bypass pipes when you do your new exhaust.

 

Luis I have them on and LOVE them. I can not drive them for a day without someone commenting on how awesome they sound. They save about 45-50 pounds from the rear of the car. This in itself is a nice performance gain becuase weight removed from the rear of a 911 is always a nice handling improvement. I would def recommend them. If someone would get out and video tape the exhaust I would love to post sound clips.

 

doesn't fabspeed have a sound clip on their site?

it is nice to see someone being honest about the HP gains from bypass pipes. if i had a dollar for every thread i've read where people claim big improvements and HP from mufflers on these cars, let alone bypasses, i'd have a nice retirement account going

 

bypass pipes dont give any hp, maybe a few if that. more for the the less back pressure and sound.

 

tell that to the rest of the people out there. zerotek really makes some interesting claims. tons of people claim 10hp just for mufflers, let alone bypass pipes.

 

the ones on the fabspeed site do not really do the pipes justice. They are much quiter in the clip than in real life.

 

And they are on a regular 996, not a GT3.

 

So you think you are better than me???



Which is quieter, muffler bypass or cat-delete (test)pipes?






.

 

Yes I do.

I think that on a 996 the cat bypasses will give you some CEL's. I had cat by-passes on my 993 and it sounded perfect. I have heard some 996's at Sebring (with Depdong) with the muffler by-passes that sounded awsome.

 

I also have installed the headers, kept the factory cats (NO CEL) but installed the bypass. No significant HP gains but it sounds AWESOME!!!!!