I think he said the resonance pretty much went away after he added the Akrapovic slip-on. That was before he added the PCV and Arrow headers Funny how that resonance with OEM muffler bothers some people while others barely feel it. I just heard from another member who had the Akra, but switched back to OEM because the Akra shifted the resonance to a higher frequency vibe that he couldn't put up with. I guess we're all made-up just a bit diffeent. Funny, this sensitivity thing is. 8)