I'm considering adding an exhaust cut out on my 3" cat back pipe just before it turns up to go over the rear. About a 3" header collector turned backwards with a cap plate. The idea is to bypass the muffler during drag runs. Has anyone ever tried this? What were your reults/opinions?

 

its populer just do a little looking around in here

 

I did this. I had a new 2.5" catback exhaust when i bought the car, so it was still pretty quiet. I pulled out the cat, upgraded the y-pipe to a 3" and met at a 3.5" cutout, reduced to 2.5" to fit on my catback. I also upgraded to headers.

I did some reading, and some people suggested, that depending on the side of the headers, the 3" would be too big, and with the dynamics of flow, it would start a "swirling" action at the cutout, and actually SUCK in some air.

I havent tried this under controled circumstances, but i can tell you 2 things for sure.

1) When you unbolt the cutout plate, it is DEFINATELY much much louder. Even with the relatively large exhaust i have. This is important because noise is an important factor when buying this.

2) It is DEFINATELY more powerful. ie: I havent been the strip with it yet, but the change is immediately noticeable. The pedal feels lighter, the car just WANTS to go all the time, and you can just feel the low end power.