what kind of fuel additive do i use, this is the first time ive heard bout it. what is the best to use.

 

What are you trying to do? If you just want to clean the injectors then they're all pretty comparable, but if you want increased HP: I like to use the 104+ octane. I've heard a lot of people swear by the seafoam treatment for the injection system, but I just usually buy whatever's on sale. Hope this helps.