Of course the bike and software is designed to run on 91, 94E10, 95, or 98. The recommended is 95 which is probably a sweet spot for the ECS and spark timing. Whilst Iím sure all are safe for the engine I doubt that all produce optimum performance. This is a 13:1 compression engine and Iím surprised they didnít opt for 98 as the recommended. Software can make anything work but high performance engines including high compression engines are more prone to preignition on lower octane and this is corrected through spark timing which prevents pinging but can impact performance. If 98 had solved the start issue for me then no issue - but it didnít. I was going to try 94E10 but decided the connectivity issue alone warranted software update. As luck would have this comprehensively fixed the start issue on 95. Was never keen to run long term on 91. Counterintuitive to everything I know about engines.