Here goes nothing!

[87National]

regarding Gen III vs Gen IV LS motors, be aware that the Active Fuel Management feature is on the IVs. A mechanic guy I know who used to work at the dealership on them mentioned that AFM lifters were always going bad, and those lifters run about $40-50 apiece...on RockAuto. He said you were better off just repacing them with standard LS lifters and then having the ECU re-programmed (I think) to disable the AFM feature.

05-06 were essentially a gen 3 with gen 4 rods and pistols. There was no AFM until 07. The 05-06 are the holy trail for low budget turbo applications.

 

[EdontheBeach]

the bottom of those engines is pretty stout right from the factory

 

[rancher]

dyno'd my 81 cutlass a couple of days ago, got 582whp with pump gas and 15 lbs of boost, a real good day.