I just put a stage one Hahn in my 02 busa and it works great. 253hp to the wheel at 8lbs. Not running hard at all, but loads of fun. Im getting rid of my full pipe that it came with though cause Ive been hearing that with the dump pipe you get better turbo response down low. I think around 3k. Right now it kicks in at about 5k. So if you want the full system, get the Hahn with the dump and Ill trade you straight up! Just a thought. The only thing to look out for is the customer service...........horrible!!! Hahn makes a great kit, and thats about it. I would suggest going through Powerhouse cycles in NY who specialize in turbo busas and sell Hahn kits. I went through them and they've been nothing but helpful with my questions. The web site is fastcycles.com. I got a few pics of my bike on there as well if you wanna check em out. Taken by the owner himself. He actually came down to VA from NY just to check out the bike and make sure everything was runnin right. Cant beat that!
Anyway good luck,
BTW they are selling that kit with the dump pipe for I believe 3,150! Beat that price!
Peace,
PWRJUNKIE80