he he... and your blaming it on mac...

 

Dude...I've got the same thing-sometimes. It only happened after I had my o/r X put on. At approximately those same RPM's, sometimes, I get the same type of noise you describe. I hate it when it happens because it makes it sound like my car is a POS and is falling apart...I haven't done much to try to locate the source, except I did jerk around on my exhaust while the car was on a lift one day and I didn't find anything loose.

I'm clueless as well.

 

Yep exact same thing here dude. It has got to be the resonance and vibration of having an off-road midpipe on our cars. I really don't want to ditch my pipe for a catted one. I'm going to try to get the to bottom of it and fix it. I don't know what will happen though, but I'll keep ya posted.

 

Going catted will still sound loud as hell. Just more tame. No unessasary rasp, or at least much rasp.

I'm trying to remember back wehn I had a MAC catback... I can't think of anything making noises.
But I bet it is just a resonance thing

 

same problem here around the same rpms at first i thought my magnapacks were loose but checked em out and they were snug. it is just a really annoying sound

 

mine doesnt do that so you cant blame it on the fact you are uncatted. i dunno man maybe your prochamber is messed up. swap it witht he stock one and see what happens

 

When I had an O/R H with Flows there was absolutely NO buzzing at all! With my O/R X there is a buzz to it around 2200ish rpms. If I were you I would go with an O/R H.

 

My friend is determined to find a solution to this resonance which is causing a horrible vibration throughout the undercarriage of the car. The Flowmasters and Prochamber causes such a deep sound that everything shakes under there from 2300rpm+ basically. I am not giving up. I'm pretty happy with the Prochamber/Flowmaster combo, and I'm done spending thousands of dollars getting my car sounding the way I want it to. Going to try to find a fix, someway, somehow. I'll let ya'll know what I find.

 

I am looking for an update on this issue. My 99 GT is doing the same thing. Put a Mac catback exhaust on it, stock mids w/cats, stock headers. Crazy buzzing sound from rear passenger side at @2500-3000 rpm. Took the tips off, and angled the "L" pipes at the ground and drove it around for a while... buzzing mostly gone, only faint. Put the tips on, and its back!! Thought it had something to do with the tips rubbing against the gas tank cover, but that doesn't seem to be it.... I even spent 20 mins laying in the trunk while my wife drove it around to see if it was the trunk lid, or something in the back... could find NOTHING that was vibrating... At my wit's end... Anyone got a solution for this?