First, welcome to the forums. You should check the Perfomance Pursuits forum first and post there next time. There are a bunch of posts about the different products. You might want to also check the archives and do a search as there were some helpful threads a while ago. I think what seemed to work best was to get better rims. The lighter the rim the better. The other point was to have as light an E overall as possible. That is, an E without extra weight like side steps, rear seats, cargo in the rear will perform better. I think what people seemed to say is that most of the products out there only marginally improve hp or gas mileage. There are a lot of cat back pics around here to take a look at. I would say the most popular mod here are the rims and tires. There are a lot of pics of those too. Things like the air filter / intake and the chip mods are less popular.