What causes it?

Is it detting or something else?

I'm running a sti V5 and as far as I'm aware its on standard mapping and is alway ran on optimax. On WOT I can see the odd orange in first and second but only greens in the higher gears but can get red when lifting off quickly. The knocklink is set to max but I'm told that's where it should be.

I know a remap is the best option but lack of funds mean it'll be a few months before I can have it done. Will octane booster cure it in the mean time?

Cheers

 

It may be lift off det. I would check/replace the spark plugs (with NGK PFR7 if you are on original plugs) and run octane booster initially. Get the MAF and lambda sensors checked, as well as the fuel pump (check pressure on full boost) and AFR on wideband if possible. Carbon deposits (from failed lambda = rich) or dodgy plugs can create hot spots that can cause pre-ignition, as could a lean condition from a failed MAF.