I wouldn't think you could get the header section to fit, and I wouldn't recommend it anyway, since the engine are so different.
As far as the mid-pie and muffler portion goes, it would be basically the same as adding any other slip-on. You likely WON'T be able to use the GSXR mid-pipe, but you may be able to cut off the stock Bandit muffler and use just the new muffler section of the GSXR on the old Bandit mid-pipe.
Performance gains will be modest, at best, but with a proper jet kit you will pick up a few horsepower on top and fill in some of the flat spot from 4-6,000 rpm.