Originally Posted by Chip

higher compression is better for low boost and n/a applications, partcuarly at high rpm, low boost the opposite.

basically if the compression is high and you get a good fill of the cylinder (ie low rpm and high boost) then you end up risking detonation unless you retard the timing an awful lot, and then that can lose you power

rally cars break the rules seemingly, but only because they run very high quality fuel which means that detonation is less of an issue

I suspect you would get EGT problems if you filled a WRC car with 97 ron fuel and remapped it to work on it, especially if you then held it under load towing a caravan up a hill or similar