Where it leaks at the joint, use some high temp RTV. Used to have to do it on both my 98 XC 600's at the can, and my buddies 98 XC 700. It was common for the U pipe to leak.
I am not sure what the 3 bends after the muffler means. Are you saying the pipe itself has 3 bends, or does it really have 3 bends after the muffler itself? That would be really odd if that was the case.
If it is the pipe that has bends, they are designed that way to make the motor run properly so just don't mess with it would be your best option like I said earlier.
01 XC 800 - 136x2", V-Force3, clutched and geared
02 XC 700 - 121x1.25, clutched
A bunch of old vintage Polaris sleds...