white spark plugs
 

Just changing my spark plugs as part of a service im giving it, and the plug tips are white. The plugs are currently ngk prf6b's and the car runs a full decat and a power fc etc and runs okay. I know white means the plug can be to hot so going to ngk prf7b's is this liable to make the car run better?
The car did run okay before anyway but I was/am a bit worried about the white colour as this could mean a number of other things different to heat grade etc, like incorrect timing, incorrect fuel mixture etc. Knock count sometimes goes into the 20's on the commander and today I had a 36 but I put that down to going to hard when it was cold.

Am I worrying about nothing