Just as posted above....don't waste your money on high test. Computers are set up for 87. They do not like 93! It will actually make the engine run even more rich than it normally does and will turn the transom black.

pcm is programmed for 87 anything higher is a waste of money.

YUP ...........

Common misunderstanding that high octane means more hp. Higher octane burns slower which is needed on a high compression (or blower) engine which will allow the engine to make more power with the compression and advance. High octane in a engine designed for 87 octane will lose power.

Very few engines are designed for high octane fuels anymore. As mentioned above, high octane burns slower allowing for long combustion strokes. Lower octane burns faster for the shorter strokes. The mentality of higher octane is better came from the 50's and 60's in the era of big block long stroke engines and everyone associated premium with higher HP.

496HO's can be ran on either 87 or 89 octane. Might be okay to run some 89 in ethanol fuel that has sat for awhile since ethanol fuel starts degrading in roughly 30 days.

Look in the technical forum or his web-site and click on the big red button on the left. bobl dyno'd both 87 and 93 and posted the results and a lot of other good info. 87 wins.

How about the whipple stage 2 reprogram? It states 91 or better?