no machining, just some very slick work by the shop that we deal with. i have a custom cut plate, afc mods, 4gsk, their cut dv's and some precision tuning. they spent 4 hrs on it. each gov takes a dif combination of springs to be precise and to work properly. it is be far the best mod i have done to the truck. it runs so much better and just woke the motor up. i gained 100hp from that mod. with very conservative timing.