yeah, youll notice a difference, I had a PP3 and thought it was cool till i got a custom tune. Now i wouldnt even think of any thing else! also allen gives free retunes so if you change something or want some thing different you can change. With proper tuning your motor will be at peak effeciency and as long as you drive wisely MPG will not suffer. When my truck was stock i saw 2 + MPG with A good tune, C.A.I, Exhaust mods.