A cpi piped stock motor is a fun bike to ride. Mine had 18cc domes,+4 advance and 35 pwk's but made decent bottomend and pulled like a frieght train from bottom up. A cpi may be considered a "drag pipe" but i think they're the most fun play pipe on the market. I've been around sst's, fatty's, procuircuts, T5's, and 6's and they're better than stock but since you've been riding the cpi's the rest will probably disapoint you in the mid and up power department.