I first installed catted-X and left stock catback on. Felt increase in power. Later I added magnapack catback. No increase in power but definite increase in attitude and drone. The drone around 2k rpm gave me a headache. I bought Bassani baffles to tone the drone down which helped. Like some previous posts, once I put the packs on nobody would pull up next to me at a light even vettes. Most hot cars stayed way behind me. Driving by a crowd always brought attention. I got stopped by a cop just because it sounded like I was going fast (no ticket, just a warning). I got tired of the louder exhaust and added attention and sold the packs for magnaflows. I'm much happier with the magnaflows.