Nightbreed
Psyco said it the best when he said get a recomendation. I do not run .15's ...yet
But get the locals that do run a nova pipe. Get the pipe for a .15 as psyco said. They have the proper backpressure for the engine and will run much better. Look on this site for Buster Bennet, he owns a LHS in DC and can help you.