I am open to doing a RPM limiter. I think the market is pretty limited for this need. Therefore I am not really open to doing it for free since it is probably 2-3 hours of work. If you really need it make me an offer to do it for you as a custom chip. I do custom chips for people at no cost when I think there is reasonable demand for the feature. For example here are the custom features available now:

Cessna 337 chip (doesn't idle engine if one dies and full power is not synced)
Dual RPM readout
PCM disable
and a few trick modes...