The X pipe adds power all across the board. I mean from idle to redline. Whenever I take my x pipe off for smog (and this is before the blower also) I just cant stand how much slower and gutless my stang is even if it is just for a few days, it SUCKS!! All the people who are saying it is tinny, crappy build, losing power are all the exact same people who DONT OWN ONE!!