You want aftermarket exhaust header I'll assume? A poplular mod without going full exhaust in order to eliminate the catalytic converter on the 08-09 ('10's didn't come to the U.S.), was to use 06/07 OEM 600/750 header with an 06/07 aftermarket slipon. HP gains of 1 or 2 (if that) vs cost for full exhaust isn't worth it generally speaking.
I just sold my '08 750 and haven't put my race parts up for sale yet. (hopefully today) Put it back to stock/street and have most items that you would be looking for... LMK what your looking for, I might be able to help (541) 401-461(one)