My 99 Z28 has heads/cam and a Borla (plate with the smallest hole). I have the MAC headers. At first I had the Mac y-pipe with cats and it was loud but sounded OK.

I recently put on the Mac ORP and OMG it makes the most horrible raspy, farty, shitty resonance from about 2-3K rpm. Is there a fix to this? or I'm going to put the cat pipe on again. Any help is appreciated.

George

 

do you have the flowmaster collector? i heard that helps some and also putting a bullet in the i-pipe is supposed to get rid of rasp too.

 

I had to order a 16" x 3" bullet muffler (dynomax/walker) from summitracing.com. It'll fin right before the intermeniate goes over th axle. No more rasp! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Thanks. But if I have to put another muffler on it, maybe I should just get a different exhaust system, like a Hooker or Flowmaster.

It doesn't have a different collector or any of the other mods that people do to MAC headers.

 

Try the collector, some have been able to get rid of it with just that. Macs are notorious for rasp. If the collector does'nt kill it all, a bullet should take care of the rest.