I would stay away from pump gas on an RS. It wasn't mean to run on that low of an octane, and you will be creating so much carbon build up, your rebuilds will take twice as long as you clean the flapper valves, exhaust ports, and chambers of the crap.

Use a good quality oil with a higher octane race gas mixing at 24:1, with a richer main, and the top end will go the full 300 miles between rebuilds.

Thanks
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Charles Gallant