The T50 Torx socket bolts that are used to secure the muffler to the turbo on the Sidewinder and Thundercat / ZR9000 are awkard to remove.  The service manual indicates the use of ball end T50 bit.  The ball end makes it possible to get at the bolts from an angle.  However, the part has been discontinued by both Yamaha and Arctic Cat.  We have sorced this hard-to-find item and have limited quanities in stock. 
 
Using this bit with a 1/4" socket with extension makes removing the bolts from the muffler much easier.