issue with spark plugs on SR.. heat range?

[Silverbullet]

ok heres the deal, my motor is breaking up/missfiring when i dog it (heavy load). I've noticed a couple things about the scenario. It's more prone (more like all the time) to do this when the air temp isn't as hot AND i been driving like a normal commuter (barely hitting boost). After i do drive it hard for a little bit (not dogging it, just hard), it dosn't seem to break up as much or at all when i do dog it.

Now, this leads me to believe i should change the heat range of the plugs im running because it obviously runs like it should when the internal temp is hotter. Oh, my gap you ask? I've tried all sorts of gap (.25-.30... afraid to go any lower), and i really dont seem to notice too much of a difference. So anways back to heat ranges. I'm running NGK OEM blah blah blah heat range 6. The ones that everyone runs/ tells everyone else to run. The lower the number, the hotter my combusion chamber will be (for the numb represents how much heat is removed) correct? Browsing around on the forum, i do not really see anyone talking about running heat range of 5. I've seen 6,7, and even 8 some times.... whats the deal ith that? my motor isn't heavily modified, just basic bolt ons.

Most people say running hotter plug (lower number) will have higher chance in knock. But here is my take on it: Most ppl run Walbro 255 fuel pumps with stock FPR. I dont know why most ppl dont know but the Walbro is too much for the oem FPR and it tipically runs 10psi higher than factory spec causing most ppl's motors to run rich. Thats right, Nissan didn't make them rich, thats just silly, its the Walbros =b. I think the extra fuel is plenty compensated if say my motor does get too hot which i dobut it will because the plugs obviously rn't getting hot enough as of now.

any yays or nay's or even just comments towards my master JDM tuning ideas? Any +/- response would be greatly appreciated.