I've just been given a yoshimura slip on silencer for anniversary to fit my yz426f 2001 running full ss valves etc 2002 clutch and everything else stock just going to start repairing 5th gear slipping ill be tearing it back down in next couple weeks. But the can on now is pro curcuit header and pro curcuit mid pipe that has been welded and fixed permanently to a 2002 426 stock silencer (so I was told when purchased bike). I've got a front pipe that came off a yz426f but he thinks it was originally on 450 and a mid pipe from same place he had it around as spare. I've recieved them but can't get access to my bike for 8 days. These seem slightly smaller inner diameter but around 24mm longer to end where slip can on. My worries is will it all fit in together.