Vara, basically as far as cost I mean alot of perf. parts are more costly...not as much to choose from, especially when you get up into the 6500 RPM + teritory, not as much to choose from in pistons, rods, cam choices are more limited (unless you do a custom grind), intakes, & well heads for that matter, all this doesnt mean much if you already have everything...or arent building anything that requires some of these perf. items