You would probably want to turbo the engine first. Propane wont allow the engine to intake air any more efficient then stock. Propane just replaces some of the air and makes it more volitile(spelling) during compression. Youll get a lil more low end torque and its always hard on the lower end. Ive seen ebay junkyard aftermarket turbos for non-t trucks and you can always make your own if you feel confident enouph with welding or plumbing.