I just bought a 2002 c32 with 55K miles and am looking at mods. What is an sl55 splitter and what is the cost? Also I see lots about the pulley's. Can someone give me a list of mods, prices, and HP gains, as well as the links as to where to purchase?

the sl55 splitter is a smoother connector in front of the throttle body. I suggest you do a search and you can find out most anything you asked, and or check the websites of the tuners themselves.