From another post on the forum by carnivorous chicken:
Yes, CB400F exhaust bolts right up to 350F engine. A couple things:
-- You won't be able to use your stock CB350F peg set up, which isn't such a bad thing. The 400F pegs were set back about 6 inches, sort of semi-rear set. On the 350F the pegs sit in front of the mount, on the 400F they sit behind it.
-- If you use the 400F pegs, you'll need to attach the linkage on the left hand side (piece of cake, bolts right on), and you'll have to do a small amount of finangling to get the brake lever just right. The brake lever switch and original mount on the 350F will work, if memory serves me correctly (or I might have added a spring to the switch to make it longer, can't remember, but can look later this afternoon).
-- You will have to work up a mount for the exhaust in the rear. This was super easy -- just a store bought bracket, and I used the mounting hole for the 400F exhaust.
-- You won't have to rejet your carbs, unless you are going to run them straight or with non-stock exhaust, or unless you switch to pods. I guess it depends on what you're running now for exhaust and air. I kept my stock airbox, switched over to the 400F exhaust with stock muffler (from a shitty Mac 4-2), and just did minor adjustments in mixture to keep it running fine.
