do i need to gap my plugs to .38 or .44? forgot its a d15b on 8 psi from a 14b turbo hf mani and dsm 450s ngk r5671a-8 plugs bout to replace them cause mine are fouled from its first time at the track...

 

I wouldn't go more than .032 on your plugs. The whole point to gapping the plugs smaller is to not have the boost pressure come in and blow out your spark. If your really not sure than call NGK if thats the plug you are using. Call their technical line and they could tell you what plug, what heat range, and what to gap the plugs you are going to use. Use at least 1 step colder if going over 5-8psi and 2 step if over 8psi. I gap my two step iridium plugs to about .028. Here is the number to NGK Technical Support
hours: 8:30am - 5:00pm Monday-Friday EST
tel: 1-877-473-6767 prompt #2 Good luck

 

[QUOTE=TurboEK9Coupe]I wouldn't go more than .032 on your plugs./QUOTE]

agreed, im at .024 here

 

.030 on mine with 10lbs of boost, no issue.