So for a dohc motor the temp stock is 6, and if you go FI you go to a cooler plug, a 7. Now my question.....If i am N/A with higher compression, and built up all the way around, would a warmer plug, say a 5 benifit me by burning warmer, i.e. more completely? And if so, use the same gap?

 

no....use a 7.
the general rule of thumb is, one heat range colder for every 75–100hp you increase. (as per NGK)

most likely your motor will reach higher temps with a higher compression.

 

what would happen if i used a plug that was TOO cold? Nothing? What gaps do you guys use/ I use 45.

 

your motor might run too rich and you'll get black "sooty plugs" because the plug firing-end does not reach it's self cleaning temprature (usually between 400-450 degrees C). Mind you, it's better than running lean with a too hot of a plug, but this just shows how important it is to choose the right plug.

it can be minimzed with a good a/f tune, but bottom line is you're not getting maximum efficiency out of the motor (and the plugs will wear out faster).

My advice is to start with one step colder (NGK 7) and go from there. Also be aware, that some companies denote their temprature range differently. For example a higher number could mean hotter for one company, where as it could mean colder for another company.