Hey guys i have a 2500hd 6.0 truck. I have obx long tubes 2.5 ORY bolted up to a corsa sport cat back. I love the way it sounds at idle, and at WOT but when im crusing at about 1/3 around 2-3k rpms it has this annoying *** machine/pop sound.
what im tring to figure out is if i go to 3 inch y after the collector would this help? also the obx y pipe has these little resonators in them. idk if that would be he cause or not. catback is 3 inch as well.

what do you guys think?

 

guess a dynomax bullet would work lol.

 

I have american racing long tubes, gutted cats, the mid pipes go to a Y and then into the corsa muffler. I too had a very annoying raspy sound emitting from it. I slapped 2 eBay bullet resonators into the mid pipes (one on each side), and that definitely did the trick. They're just basic resonators with fiberglass packing. I plan on cutting out the cats entirely and replacing them with electric cut outs, and also removing the resonators, and putting in an X pipe. Not sure if that helps you at all.
Only reason I'm removing the resonators that fixed the rasp, is because I have a feeling the x pipe will have the same results, but it will yield in a much more free flowing exhaust, rather than one with restrictions (ie. resonators and cats)

 

The sport muffler is known to do that without cats. You are not the first to complain of this by any means. It's just the nature of the corsa muffler. It's what gives them the perfect amount of raw sound with a stock manifold and catted mid pipes.

 

hmm looks like ill have to come up with a y pipe. luckily so far i havent had any fitment issues, everything i bought was used off 1500 trucks, other then slightly higher mounts (taller frame i guess) i havent had any issues. I guess i could cutout the mini resonators in the obx y and install some larger ones.

 

When I fabbed up my own Corsa using only a Corsa Sport muffler i read about people having this issue. What I did was throw a medium powerstick in right after the Y pipe. So my setup is Pacesetter longtubes, no cats, Pacesetter Y pipe, Classic Chambered powerstick, Corsa. I never had the sound everyone has but like I said I also threw the muffler in from the beginning.

 

A bullet muffler in front of the corsa kills most of the rasp.

 

just picked up a dnyomax bullet hopefully that does it