Sorry, if the truth disappoints you. The under drive pulley will gain you one hp on average. Unless you are the type of person who jumps off the line. Then you will get all 8 hp. This is known as market hp.(I have explained mh in more detail) I own one and please do not think of me as a hypocrite. I would rather you know the truth before you buy one.
new engine,1.7 rocker arms,Pipes exhaust, shorty cats , shorty headers,under drive and overdrive pulleys,4.2 upper plenum, throttle body spacer, cold air intake, stage one clutch, shorty shifter, and tune. 8.8 in storage