I want a set of of 3.0 headers in a bad way. I just can't justify the price.
The factory exhaust manifolds are really bad but, they flow everything that the intake manifold can feed them. In order for headers to do any good at all you'ld first need to find a way to gain flow on the intake side. Cold air kits and fancy filters don't do much for the flow for the same reason. Some one needs to cast up a higher flow intake manifold.
Roller rockers are worth every penny but, The gain is hard to find. sled fulcrums are real power robbers and make a large amount of heat. With rollers the oil holds up almost twice as long. The gain in torque is small but, it increases the RPM range down a little lower where you need it.
On a stock motor the headers will gain a little sound quality but, thats about it.
The bottom line is: 3.0's like RPMs. Keep the RPM's up and you will gain gas mileage(yeah, I know it doesn't sound right) and horsepower.