I notice that alot of the guys we ride with are running VERY large end caps. So big I wondered what was the benefit of it even being there? None of them guys have any packing either and some have just taken the cap off entirely. I tried that but it is LOUD!

 

The larger end cap will let the engine breath and make more HP. The down side is it is louder. Taken every thing off will not improve performance only make it louder. It might even hurt performance of a 4 stroke engine. The 4 stroke needs back pressure to work at its best. You will lose performance if you remove too much back pressure.