Yup - detonation = knocking... detonation is NOT your friend. It is not a GOOD THING (*TM). If you hear this noise you should stop accelerating immediately. Detonation causes all sorts of problems, to mention a few - blown plugs, broken ring lands, melted pistons, burned out exhaust valves etc....
Brakes pads for an R33 - talk to Perth Brake Parts. Use Bendix Ultimate - nothing less or you will be dissapointed.
This has been a community announcement fuelled by red wine - not to say that the information is inaccurate, cause I know through experience on both counts that I'm correct! I hope it has been helpful.