I've been interested in the "Gundo hack/FisterD mod" of the cans for awhile. Procured some spare cans on ebay. Ready to try it. Searched (yes, SEARCHED) forums for any info that I may have missed.
Well, I found a post or two saying that decreasing backpressure (which this hack will do) will cause a decrease in torque (and possibly a very slight gain in HP at top end, which I don't care about).
Anyone who's done this hack notice a difference in torque?
All the ads that promote "free flowing exhaust" and "less backpressure" make it sound all good--they never mention a decrease in torque.
Any info would be appreciated. May have absolutely BLOWN 25 whole bucks! Maybe make a garage decoration out of them.

Jim

 

I have Bypass pipes and they definitely create less back-pressure and there is a small, but noticeable, loss of torque below 3k rpm.

I don't think the hack mod creates less BP than bypass pipes. Its probably so small of a difference, you wouldn't detect it.

 

I too have the bypass pipes and dont' feel a loss of torque. I do however 'feel' loss of weight from the rear 40+ pounds. Maybe it is just me but the bypass has really awakened the car.

 

I have the FisterD set up and love it. No noticeable loss of power-the sound definitely give the perception of being faster. Have you seen any dyno reports showing the decreased torque? I'd be interested in what the number really is and how it would truely affect lap times.

I'd also like to know before/after lap times with PCM programming with packages like Softronic, REVO, etc.

 

Larger pipes will give you less torque. (I put the X51 headers on my S with PSE and only notice the minor sound difference). No sense of any loss of torque.

 

[QUOTE=BlueJay73;5530539]Well, I found a post or two saying that decreasing backpressure (which this hack will do) will cause a decrease in torque (and possibly a very slight gain in HP at top end, which I don't care about)./QUOTE]

From what I understand the problem is not decreased backpressure. Less backpressure is always good for an engine because it's less resistance for the exhaust to exit the engine. A loss of torque is from the decrease in exhaust gas velocity causing stagnation in the exiting gas flow.

This is a good article http://www.sportcompactcarweb.com/te...ems/index.html

 

By the time the exhaust reaches the bypass pipe on the muffler, anything that could happen has happened. muffler mods with no other mods make no differences. Your cats will kill all the power you'd pick up if they weren't there or had sport cats. The muff mod that Darin does is for noise only, you want power gains, go with sport cats (or no cats) chips etc......

 

Yes, but do you 'awaken' the neighbors, too?

Seriously, how would you compare the sound level with the bypass to that of FABSPEED or PSE?

 

My muffler modifications are similar to PSE, but with no "shut off" valves. They create a great tone, more aggressive then stock, but not obnoxious. They are strictly for sound, even though they do give the muffler better flow. Like Chris said, don't expect much power gain/loss from a simple muffler change. Although many people tell me their car feels less sluggish with the new exhaust, I think it's the perception of better sound that makes it feel this way.....you know, like when you detail your car, it seems like it runs better!

 

Yeah, I feel the same way. I did a run up to Mt. Palomar and the sound was great for heel&toe, responsiveness seemed better, plus being ~40lbs lighter didn't hurt on the twisties....

It is loud, but it's like race-car loud, definitely gets attention!

Has anyone tried modifying byapss pipes to quiet them just a bit?
That would be really perfect for me, just a touch quieter....

 

When I was on the Palomar run last weekend, several guys said "that's the best 996 I've ever heard" and "the car sounds great from 4 cars back!"

I justified it as my neighbor has a very loud/lumpy 427 Vette, and I thought how much louder could bypass pipes on a Flat-6 be?

It is really amazing but also very loud though.
But I can putt-putt out of my neighborhood and only true car guys look.

 

Amen to that. It is louder but positively louder. It sounds nothing like the muscle car guys with their obnoxiously vulgar displays of power. The FabSpeed muffler delete is by far the best mod I have done on any car.