Don't waste your time. Those things create turbulence in the exhaust stream. Turbulence = backpressure. They will quiet things down, but at what price? I would highly recommend another solution. On the other hand, high flow cats have been proven to create very little back pressure, have almost no effect on performance and can help make your vehicle a little more friendly to the environment.

 

The high flow cats will definitely reduce the noise too...mine went the other direction, my exhaust got extremely loud after I gutted mine, so the cats were definitely serving as resonators when they were there. I got the same effect when I gutted the single 3" cat on my 85 MonteSS, only I felt a bigger performance increase with that, as I assume the catalytic flow technology wasn't as superior in 1985.

 

+1 for the big body magnaflow...i have a 22" 3.5" in/out on mine and there is no rasp at all

 

if youre looking for something small and compact that dont hurt flow try classic chambered or sweet thunder chambered mufflers.

 

Those sweet thunders sound good, I think I will try them on my next exhaust.

 

StrokerAce has them on his truck it sounds pretty damn good to he had a vid on here somewhere

 

Well guys after all the negative things Ive heard about these things I hesitated about installing them tonight. Im thinking of returning them for a pair of Magnaflow Spun Metallic high flow cats (59959) instead since they fit my space requirements. Do you think they would get rid of my rasp problem? Or could I get away with ceramic ones? They will be mounted directly on the collectors, I dont want them to melt. I am looking to quiet it down as much as I can. Any ideas?? (without cutting up my cat back).

Here are some videos of my current exhaust.

Revs

http://www.youtube.com/watch?v=Z7lROgKAMiw


Acceleration

http://www.youtube.com/watch?v=BCazUL7EWBE

 

The spun cats are great. I had a set before I went turbo. No rasp.