antijam
CCCUK Member
They’re an insulating boot to protect them from the exhaust heat.
If you've got headers fitted (as I imagine Oneball will have) you find the leads run very close to the exhaust and insulators are essential to protect them. (I have black ones on my 350 - a little less ostentatious than the silvery ones.... )
Your car has come on leaps and bounds since I saw it a couple of months ago, Tim. Are you predicting a completion date yet?