A turbo on a 602 C.I. inline six gas motor is actually a waste of meoney, time and effort. If you just need the turbo whine, go with the diesel. To make more power out of the 602, you need to look at two areas to improve BEFORE you break open the motor, Intake and Exhaust. All a motor is, is a Vacuum Pump. The more air you can get into the combustion chamber ( Via- better open intake system, instead of stock BOX, better carb (Zenith does wonders) and the more air that you can get at, at a faster rate ( better exhaust system, more open muffler, not 40' of pipe) the more power you will make. Remember this is a very large straight six, with a HUGE reciprocating mass (Crank, rods and pistons) that does not need to turn high rpms. A good running and tuned 602 is not fast by any means, but it will pull anything you will ever need to drag. I have done a Zenith carb, very open filter cutstom airbox, and installed a low restriction exhaust without any tight bends, and it is no slouch, spinning 14:00/20's the whole time. The best mod to start with is to improve with what you have stock. If you try nitrous oxide, it will wear your lower crank bearings out fast, unless you have a tight, freshly built motor, or one in excellent shape. Nitrous causes a much higher compression, which tends to "drive hard down on the crank, of course,", and trys to push it out the bottom. And since this is a slow revving six, without a stall and a auto transmission, the truck will not let the motor spin but sooo fast, and that compression will probably go past the rings, into the crankcase for some negative crankcase pressure effects ("hey, why is that oil leak popping up now?". I've tried a few things, except a turbo, and It was always better to improve on the stock design at rebuild, try to get the compression close, but no higher than 9:5-1, and polish the exhaust runners, have a Good valve job done, and mill the heads to have a "true" flat, sealing surface for the gaskets. One thing sometimes overlooked is deck-surface flatness, so always lay a straightedge on the block head surface, and check for warpage. I'm sure some people won't agree with some of this, others probably will, but it comes down to how much money you can spend on your project, and what you want to do with it. Hope I was helpful. Steve