42.5 is the jet that's in it along with a 122.5 main jet. You may or may not have to jump up the jets if you install a different exhaust. Just richen up the mixture screw and raise the carb needle for the time being,then if you do any exhaust mods you will be able to tell pretty quick if it needs a higher main jet and pilot if it hesitates on take off and even then a finer adjustment on the mixture screw maybe all that's needed. Lot of times stock jetting may be ok with an aftermarket exhaust,you just have to test it out and always check the spark plug to make sure it's not a whitish color(too lean) OPT

 

You want a #45 jet. You have a #42.5 now.

 

You beat me to it, OPT.

 

Gotchya on the #45 jet... It was getting late and I guess I miss-read it, but thanks again guys. I'll report back my new findings after I'm done tinkering with it today...

 

Any pictures??