ok now i have heard so many rumors about octane, some about how its only purpose is to prevent knock and has no effect on perfomance. So I have to ask, would putting a higher octane fuel or even racing fuel in an LN3 have any sort of effect, or is that only for */Ced engines?

Yes, higher octane fuel will show minor gains in almost any application.

However it is most noticable in the SC motors. I never noticed a difference in my 5.3L truck. Not a bit...mileage wasn't enough of a difference to see.

ok i have also heard that a higher octane fuel will cause you to get better gas mileage, now IS THAT TRUE???

I seem to get less gas mileage with higher octane

Most will see a slight improvement. Some have a foot issue that gets worse with higher octane. See John'* (Mos95b) post. lol

any specific brand of gasoline or just in general?

so the basic answer to this post is ....

YES for */C

NO for N/A stick to 87-89 octane

what about SC running 87-89??