I wouldn't waste my money on aviation gas and here is why: The most common "av-gas" is 100LL or 100 Low Lead fuel. Most people assume that this 100 is fuel's octane *RATING* when in fact it is the octane *NUMBER*. Octane number and octane rating both quantify the fuels anti-knock properties but they are caculated differently and have different values. Essentially, 100 octane *NUMBER* (e.g. 100LL) is equal to 92 octane *RATING* (e.g. premium unleaded pump gas). If av-gas has an advantage it is that it won't "varnish" and gum up if left standing for a long time.
If you are looking for more power through special fuels you might try a blend of 70% 93 octane rating with 30% MTBE (Methyl-Tertiary-Butyl-Ether). MTBE has an octane rating of 118 in pure form and the 30:70 mixture stated above has a true octane rating of 100 to 101. MTBE also releases oxygen as it burns so it has an affect similar to nitrous but on a lower level; maybe a +5% hp gain. It can be bought for $3-$5/gal. Look around for a chemical supply store or maybe find it in a paint supply store. I haven't tried this but it won't hurt anything. If you try it and get more power be sure to spread the news.
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