it is an exhaust restriction to a certain extent, but its kind of hard for me to say that, all its doing is spinning that wheel, and that shit is extremely easy to turn, shit, i could turn the turbine with my own breath, its not more of an exhaust restriction than your stock manifold, i do like the fact that a supercharger doesnt have to be cooled down and its pretty much maintenance free, but your just not going to get the power from a supercharger that you can from a turbo, but the torque numbers are pretty fucking dope.........