The popping is normal to the AT. My staintune slip on pops, with the OEM headers. I believe the AT has air injection, and that's what causes it. @Motociclo can confirm. Mine sounds about the same. With the baffle out, it's a touch too loud, but with the baffle in it sounds like a gopher farting through a pvc pipe. It's substantially lighter, and it was on the shelf, so cost me $50 to get the welding done for it, and never needs repacking. Win win. I don't know about their claim for no re-tuning. I'm running a pcv and it works well. I think it's a must for a full system.