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					Originally Posted by  dknv
					 
				 
				MikeK ftw. 
Though, didn't we have a thread on the semantics of whether 100octane at this elevation even helps? 
			
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 It's not just the power gains as it is the safety gains.  The 91 we get from CA is crap, and it varies in crappiness... sometimes it's just normal horse-piss, other times, it's like zebra urine.  
Race gas has a much lower chance of being off much from the label, so there's less chance of getting a "bad" tank and boning the motor.  However, running 100 in a car tuned for 91 will reduce top performance slightly.  The best gas I ever used was the time Eric and I put race 92 in his STi at Laguna Seca... the car ran like a champ!
So race gas is really good for safety reasons alone, but if your car is tuned for 100... then like Mike says... it can be worth a lot in terms of performance as well.