Andy, Rogue has roller rockers for the 3.0 for under $300. It's like a poor mans camshaft and much easier to install. I've put on two sets so far. The ratio is different from stock so the valves open quicker. Being rollers, there's less friction.
Rogue's roller rockers are a great investment. They are pretty easy to install and make the engine alot quieter. With my factory 3.0 the truck idled smoother and the exhaust note was alittle deeper. With my new 3.0 they work just as well. I would definitely recommend them. You won't be disappointed.