However I already have these 555s along with a J&S knock controller so I have a safety buffer should they start to fail. If I didn't think e85 was a possibility down the road I'd spring for the 740's now but since it is I don't want to be buying multiple sets of injectors on top of paying for multiple tunes. I'm hoping I can at least get a few years out of the 555 tune before having to do it all over again.