i did NGK, wires,cap,rotor, cleaned drop in k&n, and cleaned the throttle body the other day. Still fells slow!! As for the V8, I have an 08 Trailblazer SS the Im putting a 4L80e in just got kooks 1 7/8 and all kinds of suspention mods. Im getting that ready for a Maggie next year. My 01 is my DD so I was wanting a little umff without killing the MPG like a cam would do. Now if I put a muffler and a CAI on it with a mild tune I might pick up around 30hp