I had a long interesting post ready and accidentally left the Forum messing with an email. Drat! So now a boring version of todays investigation. It's a leak, most likely at the throttle body, lower Y pipe hose or the supercharger to intercooler gasket. The engines AFR's are low 13's at WOT and I'm missing 75 hp, or more. After going WOT a couple of times the "tone/whine" returned and the idle was a bit high. It was too hot to dig in but the whine was from the throttle body/Y pipe area as far as I could tell. The car was idling fine until going WOT so my guess is some hose or joint unsealed at high boost post supercharger. Loss of hp points to a boost leak too.

All the hosed checked out. Brake booster hose, hoses under the supercharger, pvc/catch can hoses … the one under the battery tray doesn't hold vacuum but I don't know if it should or not. The A/C and brakes are working correctly.

Les