Steve,
I have the j-pipes and mounted the exhaust just last week. I didn't use the rubber mounts FFR supplied. Instead, I cut in half one of the hangars from the donor and placed it as far to the outside and as high as possible on the 2x2 square tube at the front of the footbox (per the manual). Do a sort of "mock-up" and you should see what I'm talking about. This set-up allows some flexibility in lining-up the pipes. If you use the mounts FFR supplied, you need to get the hole drilled right the first time. It appears that using those mounts will only allow up/down adjustment, no side to side movement, so be careful. I may add those after the body is on and the pipes are exactly where I want them.
Paul