If you are going to do it there are only two that I know work. There is one that may work, but I haven't tested that one. That one is called Race Gas.
The one I have tested is Torco Acclerator. I know it works. You can buy it either in leaded or unleaded.
There is also a product called BOOStane. It is a copy of Torco Accelerator. I don't think you can get that in leaded. I called them and they were going to send me some info, but as of yet I have nothing on it.
Most of the stuff you can get at backstabbers isn't worth messing with.
