the more boost you add the cooler the plug we use. 103 are fing cold for 7 psi. stock is what a 106?
when we pulley down you drop to a cooler plug, being your running less then the stock boost, the stock heat range plug will work just fine for you the way its set up right now.
103 iirc would be for like 3.0 pulley and like 11 psi
i still think this poor engine is hurt and it was turned down. those plugs say it was running way more boost then it is now. or the last owner really had no clue wtf he was doing.
fingers crossed.
