greddy all the way. it is the best design for the imports and an awesome sound w/ the best increase in hp. i had it on my b18c1 95 gsr and loved it and it had a nice tone...but not a fart cani think of magnaflows and borla for more domestic high torque engines at lower rpmswhile skunk2 might be decent, the best is going to be greddy w/ its low restriction and nice tone...add the greddy headers and i think they dyno that on a 06 civic si to get around 10 or 15 whp more