not really a response related to your issues but i'm also running gt40p's without changing the extractors (hurricane) that were on the e7's. using the original leads i had to tape up the exhaust with heat tape on no.7 plug (3rd back on pass side). i even had to trim about 2-5mm off the end of the boot to get it on the plug but once on i had about 2mm clearance. all other leads were fine.

i've since had a custom set made with 90 degreee boots and no more issues with burning leads or boots. much cheaper than changing extractors.

Yeh the ones it came with had 90 bends on it, but they were so thick they were touching.

Previous dingbat owner came up with the bright idea to bash the headers at certain places.

my stroker did this originally. TPS and idle speed set incorrectly. Idle was too low and conked out due to cam and TPS too high so EEC was using the wrong tune map to try and idle. Result = EEC going spak tryna keep the engine idling lolol.