One thing that has not been noted in all of the posts is that 100LL WILL clog the cats. It would be quite bad to give the average Z'er the impression that he can just roll out to the airport and pick up some extra power. However for those of us that do not have the restriction of cats ( for one reason or another ) it is a good alternative. Just in case you think I dont know what I am talking about, trust me I am an aircraft mechanic and corporate pilot. So I do for the most part know what is going on in this limited area.