Yes, if you don't it will run rich on the bottom. I don't know if Dynojet has the remap for the Akropovic yet I know the didn't have it when I had it done. The best numbers I have seen so far, with a pipe is the Akropovic. I had a 159ponies with the pipe alone, unfortunately I don't know what the bike had without it. With the PC2 and airbox mod dynotuned to 167.7hp, Now that is a lot of ponies and 101.8lbs. I'm sorry if I'm starting to sound like a broken record.