[DonC]

Ditto what Bob said. Took mine off a few years ago and had no problem getting them off or putting them back on.
Definitely loosen the primaries to allow the pipes to move a little bit at the joint. With my big block I couldn't really get to the bolts securing the rear primary on the driver's side but it didn't cause a problem as long as the other three could move a little.
DonC