just removed end cap and also the packing from my exhaust ,i think it sounds awsome with my new 11.5 je piston, but just wondering if you gain any performance or do i have to rejet

 

If you were running a stock exhaust you will gain performance if you jet it properly but it will be loud as hell. I would recomend at the least buying a end cap that way you don't gain enemies around where you ride.

 

You'll actually lose some low end torque by removing the stock end cap. You might consider an aftermarket end cap instead of nothing.

 

You could just cut your stocker up. Cut out the spark arrestor and just leave the exit tubes... if you want to get crazy cut a round hole that will still hold in the baffle. There are a bunch of threads about doing this... do a search, you'll find the info you need to do it.

 

When i tried that i actually lost power....it was a stock motor tho. I would cut the internals of your endcap off instead.