Spark plug heat rating?
 

My car runs a 40 thou skimmed head and about 20 degrees advance i think. It was mapped a while back and I've removed the plugs recently and they are white. A friend suggested that this means they are getting too hot and that I should change to a higher heat related plug?

I see mx5 parts do BKR6E-11 (which it already has in it) and the BKR7E-11.

I take it I want the 7E's?

General rule of thumb. 6 for NA, 7 for forced induction.

So I can just leave mine turning white?

I thought if they went white that meant they were getting too hot?

White = lean, check injectors... or fuel map if you have a standalone

Are they threaded in correctly with torque spec ?

It's on megasquirt and has recently been mapped.

I have no idea about that sort of stuff I drop it off to be mapped then pick it up done.

On the dyno printout it's AFRs looked ok but it does run a lot of timing advance so maybe that's it. It's back down for a map check next month I'll met
Nation it maybe being lean then

Higher number is colder plug.

Buy a wideband. Reading spark plugs is archaic and difficult to actually do correctly.