I've read a lot of post saying that the reducer needs to be left in. I read these after I gutted my pipes. I started with D&D's but didn't like the look or sound. I bought some stock BA pipes on eBay with three 1/4 hole drilled in the two outer baffles. They were not what I was looking for- too quiet and a big loss of performance. At first I just beat the baffles out -all of them. It sounded FANTASTIC. Not too loud and with a DEEP tone. There was still some loss in performance from the D&Ds. Being a dumble, I looked at the D&Ds and they were not reduced - a straight shot - so I figured- eh, what the heck. I took out the reducer and the corrugated hunk of aluminum (catalytic converter?) behind them. I noticed an improvement in performance. Back to where it was with the D&Ds. But they are very loud. Loud like the D&D but with a better sound- less of a blap that parallel twins make.
