I actually had a 3db increase with the soundstream amps that I had before, at first I was hitting 148's-149's, afterwards, I was hitting 152.x. But when I went to the MMats amps, I was hitting 156 and so on, but I never put it on an RTA or did any intensive tuning. I'm positive that if I would have, I would have broke 160 easily. I don't think the altenator re-winding would have made a difference with the mmats. They are digital amps, and don't draw nearly as much as the Soundstreams. Infact, I was able to get rid of the caps, cause I needed the room for the additional amp, and I noticed no decrease in SPL