First: I would like to change my gears..they are stock now but I do use my car for a lot of highway driving to and from school to home. 200 miles or so each way, I get about 25 mpg right now. At about 75mph my rpms are at 1900. How much would say 3.73's or 4.10's hurt the gas mileage and would it be worth it to go for the 3.73's over the stock ones. Second: I have been reading a lot about the different combinations of PI heads cams and intake manifold. Some of the PI intakes that I see say I need PI heads in order to bolt it on. Then when I read the NPI vs PI thread it did not sound like that was the case. Also how hard is it to do each one of these swaps and is there a certain order that is reccomended to do it in? Heads then cams then intake or something along those lines? I was kind of hoping for a difficulty rating for swapping NPI to PI. What is the hardest (heads, cams or intake)? What is the easiest? If anything is unclear just lemme know and I will try to clarify. Thanks ahead of time, If there are any threads you found useful feel free to post them. I have read most all on this site but others could be helpful.