I bought the whole msd kit. I probably could have just used the basic kit but since I found the whole kit for the price of a basic, I bought the whole thing. I removed the aux. tank mainly because I didn't need 33 gallons and I never cared for the tank on the outside of the frame rail, right under the drivers seat. I'm not 100% sure about a return line but you're not supposed to use hard lines when plumbing the MSD.