The HRC card advances the timing which will increase the risk of detonation under load and I think I read somewhere it removes any restriction in the higher gears (the same effect was wiresplicing a '21 so it always thinks it's in third) which will increase the amount of load the engine is capable of generating thus exasperating any fueling issues.

I wouldn't run it (especially at high revs in high gears) without having it checked unless I was a plug chop expert (which I'm not).

And mine both (standard and HRC 030) work on the bike with the splice although Andy says others have not.
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