Caldina GT-T detination?

[DanielA]

I've noticed recently (in the last month or 2) that on high boost my 1998 GT-T Caldina is getting audible detination. I've always used BP 98 octane with no issues. Car has a bleed valve that was in it when I bought it 2 and a half years ago but the car is only boosting to 12-13PSI which I think is standard.

Any suggestions? Someone said to look at the spark plug temperatures but I don't know what I should be using. I put expensive NGk premium platinum plugs in it a year and a half ago when it was miss firing but can't remember what they are exactly.

Should I remove the bleed valve?

[LEAKER]

viewtopic.php?t=89014

Have a quick look through this. Its not for a gtt but its a good start.