Looking to modify my stock GS 500E exhaust... Any of you guys know how or where I should drill holes? Thanks Guys

Drill Holes??? Ummm.... There really isn't a place to do that. But if you wanted to, you could drill out the space in the end cap between the inner & outter exhaust outlets.

But why not just buy a Yosh Zyclone full exhaust for 190 bucks? Or a Cobra or Vance & Hines slip-on for 99?