welcome to the org. for power you've got the Downing Atlanta Supercharger usually referred to as a DASC, which was specifically made for the M42/4, xxxjohnboyxxx knows a lot about turbos and could help you out there, i know bluebimma did an LS swap into his ti but id imagine it wouldn't be too dissimilar to swap a ford V8 (Ford > GM
) my personal favorite is a metric mechanics engine which are insane, xxxjohnboyxxx has one i believe but they cost quite a pretty penny and lastly theres a lot of guys who swap either S50/2 or other BMW 6s into the ti since they drop right in. hope this is of some help