EFI motor plugs alway look white if you pull them after you putted around town or after the car has been idling.
They run like 15:1 at idle, which = white plug.
If you want to know what your car is doing at WOT, do a WOT pass, kill the engine, and check the plugs directly after the pass. Not after the return road, but immediately after the WOT pass.
88 GT CHI headed 351w 10.8 @ 125 - still figuring it out.
03 Cobra 2.3 whipple 10.7 @ 129 - sold it
04 Mach 1 12.7 @ 109 mostly stock - sold it
89 LX procharged 302 515 hp 497 ftlbs 10.7 @130 mph - sold it