[tedster427]

Exhaust issues are always a big problem, even for the originals. 289 or 427 is a bit..! The main thing is that the rear mount isn't being forced back or forward when the primaries are loose. If this is the case ,you might have a leak or a crack appear when you tighten the primaries due to the tension from the sidepipe. This is for a 427 style, 289 style is to make sure the Rubber/Neoprene isolators are fresh. We all know to well about "old parts".
Have Fun, Thats what it's about!