My 2 cents worth. Having put 1000 miles on my Austin Healey/Trailblazer swap this summer. ( I know, it's not a truck!) The 4200 does not have a torque curve. It looks like a drawing of your kitchen table. With the variable exhaust cam it always has torque. I have a six speed (double overdrive) trans. I only need a three speed. Highway mileage is between 30-32 mpg. If you really think you need more power, why not a Rotex blower, small and efficient. These engines get 290 hp stock. Split the manifold, throw away the airbox and put a good filter on and reprogram the injection and you should have 325 hp and all the torque in the world whenever. Lyndon Wester at Wester's garage reprogramed my stock CPU for me. I spent $850 on a 2004 18,000 mile motor. $600 on the CPU,$300 on a flywheel, any chevy clutch will do, $50 bucks on misc pieces of steel plate for the trans adapter ( I didn't use the Colorado pcs, that trans was geared too low for me) and motor mounts, I milled some new alt and idler pulley brackets for a new belt drive and that was pretty much it. Oh yeah the engine I replaced was about a $4000 built up 250 chev.
