In 03' there wasn't alot of mods. I got into GP's in 05' People were tuning with AFC 2.0 controllers that helped control the air and fuel. Efficient at the time but not near as good as the tuners that are available now. I remember when i went from the AFC 2.0 to the DHP tune and then to a custom tune. It was a heck of a difference. Also in 05' you couldn't touch a set of headers for under $900.00