Like someone mentioned earlier, all the base "carrier" in gases are practically the same. Oil companies do not invest billions to make better base gas, they spend money to meet industry standards, thats it. What makes them different are the additives. The additives go to protect engine internals (just like oil) and provide for cleaner burning for emissions...THEY DO NO MAKE ADDITIVES TO INCREASE HORSEPOWER, that is octane related (but that depends on compression ratio). I saw an earlier thread in which someone pointed to specific weight as a guide to more hp. I dont follow that , b/c again, all base gas is produced to the same standards and Exxon buys from Shell, who buys from Mobil, who buys from Texaco, who buys from Marathon, who buys from Citgo...etc. They all treat the base gas as a commodity, and simply add their additives.
Higher octane ratings give more horsepower by in effect increasing the compression ratio of a given engine. It does that by taking longer to ignite under compression. Octanes, a form of hydrocarbons, ignite much slower under compression than say, heptanes, so the higher octane rating, the higher the compression ratio, the more power you produce (due to ideal gas law), PV= nRT, more pressure, more temp, more power. Now, some gases acheive higher octane ratings not by using more octanes, but by using alcohols. Alcohols are not octanes, but they do slow the combustion process b/c while yes, they burn hotter, their flames propogate slower...meaning that unless you have a high compression ratio engine, the reduction in flame speed can actually result in a loss of hp for some engines b/c the ideal flame temp has not had a chance to be reached at given piston position and compression ratio.
That is why I never use 94 rated Sunoco. Yes, it is a higher number, but it is a higher number due to ethanols or some other alcohol. And unless you are at close to 10:1, I dont believe ( I have no data on this point for Vipers, but it is true on passenger cars w/ 8:1 c/r) you have the c/r to take advantage of all the alcohol in the fuel. A 93 octane rated fuel, with it being 93% pure octanes and not corn on the cob alcohols will outperform a 94 octane/alcohol blend in most stock engines.
So, what we should be watching is the percent of octane to alcohol on gases, and not the company that is pumping the gas...b/c again, all the base gas is the same.
Just my .2 cents