higher compression promotes earlier point of det! higher combustion temps in cylinder due to the air being compressed alot more. so in theory could lead to more localised hotspots which promote the onset of det...

how ever a higher compression does give a biger bang when combustion occurs so does give more power, its just making sure the engine can cope and that cheap/bad quality pump fuel aint used to try to decrease the risk of det!

just what i have sort of learnt in the course at uni so far, prob all wrong tho!