Once you get used to that "screaming" 120hp 4.2 V8, and you will, you'll want more. But, SUPRISE, their are few, if any, mods for it. That cam and carb will add like 20hp, and then you've hit a wall. You'll just have to rip the engine out again to swap in high-compression pistons, ported heads, etc. Then you still won't have the power of a stock 5.0. Then you'll have to run expensive gas to keep the engine from detonating, so your whole MPG theory is in the crapper. Who's the "fool".