no there wouldnt have to be a end cap on it but, take your bike to a muffler shop and tell them what you want done. most of the time they can make it so the pipe will fit snug into the end of the muffler. thats what i did and other people that i have told have done in and it has worked good. there might be a small leak around where the pipe goes into the muffler but nothing bad.
-Aaron
-Aaron