Hey I was wondering whats the difference in temperature range when it comes to spark plugs??? Also which ones do you guys prefer, HKS spark plugs or ngk iridium ix, I was planning on investing some money on hks plugs because the last one i had were the iridium ix, was happy with them but wanna try something different, also do the iridium ix have the stock temperature range of 6 or is it higher??? because the hks i wanted to get were a 7, just curious