One other thing is that all of my engines make quite a bit more than the published number. For example, the last 925 efi I did made 1028 hp on 93 octane. Obviously, a lower octane will cost some power, but it will not be as far under the published 93 octane number as you would think, since they make so much more than the published hp number.
I think that is a big advantage to using a custom builder. You can have your engine build to run on whatever fuel you want. If I set it up for 87 octane, then it will run on 87 octane. It will still have the same warranty as any other engine I build. Hope this helps clear up some of the confusion. Thanks.