There is some talk on the
BayAreaRidersForum.com about the EXUP exhaust system. It's a servo operated backpressure valve in the exhaust the gives the engine much better mid-range power. It's pointless to take it off but I'm sure the carbs can be rejetted to compensate if you do take it off. I highly recommend leaving them on the bike though. My bike was sold locally and went around to a couple owners who gave up on it because someone put an aftermarket pipe on it, thus, removing the EXUP and it never ran good again. It sits in a friends backyard to this day under a tarp. Poor thing!
So don't take off the stock EXUP valve. Buy a bolt on pipe of make one but don't go any further. It doesn't need it! That bike has tons of power from the factory! Spend your money on suspension - it's a WAY better investment.
If you want to check out the exhaust talk about the EXUP and what to do when you remove it check out the BARF forum as they have some excellent advice in this thread:
http://www.bayarearidersforum.com/forum ... ost5548267