Muffler replacement huge horsepower gains!

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Originally Posted by Rare Iron

Dave, I'm not really sure what this can be. I would suspect the louvers in the flowpath are creating this, but if someone running mufflers with smooth perf cores are having the same effect, then that would blow my theory out of the water. I've heard of other sounds described on decel & in-between shifts on manual cars - like backrapping, popping, etc. This is not limited to my mufflers. If you listen to the Z06 Corvette on my website, he is running 3" Powersticks x 20" long, & he accelerates from 30 MPH to 140, then takes his foot off the gas for an extended decel. NO popping or fluttering at all, AND he was not even running tailpipes - the exhaust was dumping under the car! I did not expect it to sound that clean. He was also running into the louvers as suggested.

All things said, I'm am very pleased with the Cobra Packs.. You really have to be listening hard to pickup on the flutter. The more I drive it the less noticable it's becomes. As I said earlier, from outside the cab you can't hear it.

What I really like about the Cobra Packs are ... the rumble at idle is deeper, more mellow and best of all quieter than the Cobra Sticks were. It still screams at WOT though, as it should. The "under the overpass" melodies are very pleasing too.. .. ya jus' can't resist that throttle blip on entry to let 'em know you've arrived