I run 16" JCW shorties. It's a straight pipe, love the sound. With the 16T front sprocket on a Speedmaster, I don't really notice any loss of bottom end. Maybe because the shorties are a fraction of the weight of the stock pipes.
Steelheart- '03 Speedmaster Black/Yellow
The Hayabusa Killa
16" Shorties/140 mains/Airbox drilled
Procom CDI
"There is no cure for Celibacy. But we can treat the symptoms."