You said you were getting crap MPG's right. It is the collector. That is what made me weld mine...put in a new Bosch Race o2 after the weld too and she went from about 19-21 on the HWY to about 21 AVERAGE!! Even saw 31 at one point it was AWESOME!! WITH MY MODS TOO!! And that was with the 3.1" pulley...