This discussion has been had a few times with the result being that both aftermarket pipes avaliable motad/delvic produce similar to stocK flowrates to the stock pipes. The benifit to your bike is that you can order the motads, maybee the delvic, and stock pipes(98-99) with no inlets for o2 sensors or catilitic converters and they all will fit your bike. I went with the motads on mine for the quality of their product(very impressed) because my stock pipes were begining to show their age and did not want to replace them with stock just to rust again.
