The main reason I'm not using phenolic spacers is due to the fact that they raise the fuel injector further away from the intake port of the head in Subarus. The main reason I switched plans from the long runner na intake to the short na runner intake was due to that fact. I'd at least 13-19 mm phenolic spacers on na intake to clear the avcs on the heads.Remind me again why you didn't want phenolic spacers at least in addition? Aluminum is an incredibly good heat conductor. So right now it'll help carry block heat into the IM, which undoes some good work from the IC. If you add even a thin phenolic spacer it should interrupt some of that heat xfer, right?
I do have some 3mm ones but most likely won't be using them since that's bumping up the intake manifold even further reducing hood clearance.
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