i just put a single in dual out flowmaster 50 series on my 01 Screw
Sound is good but could be louder. I stayed away from the 40 for fear of the drone so often menttioned with it. The 50 sounds good when your on the throttle, but leaves a little to be desired at low rpms. I may switch it out for a 40 if I can find one cheap

I have true duals on an 01 Screw
 

Hey guys its possible you just have to chop that pos y pipe off and get an x pipe...I got a magnaflow SS ones on ebay. run the pipes back over the frame crossmember then add the x then run it further back to where the stock muffler was and place your mufflers side by side then run your pipes out how you like...personally i went with stock harley take off pipes it looks pimp! Also bassani is now offering universal mufflers much better sounding than flowmaster and i think a bit louder than magnaflow check out the soundclips on www.exhaustsoundclips.com Good luck