Computer tuning. Not much mechanical other than getting the throttle bodies synched. The thing is the MAP and IAC need to be on their own separate vacuum systems, especially the MAP; you don't want to share them with something else that will be using and not using vacuum (like power brakes). The brakes and pcv can share, but the other two need their own separate lines. They'll work sharing but every EFI tuner I know says not to do it.

Jody