Yes the HRC tip is a must. Stock tip is way to restrictive and it even made my engine run noticeably hotter. I didn't really do it for performance, I did the swap fror parts availability and quiet it down. It sounds absolutely great now and the DNR wont bother you and your neighbors won't hate you. Still has some grunt but quieter then a crf450. The 350 came with a cobra and my opinion is it and other exhausts sound horrible, supertrapp can be tuned to sound decent but still not my type of taste.