violacleff - The NGK engineer just said that if you are running around 250hp then the BPR7ES is the one to use. Naturally a heat range 8 would be needed for higher hp applications. I might call him back and find out to what hp level the BPR7ES is good to. I was thinking about my own application, so that is why I said 250hp.
If your plugs are turning white, it would be advisable to gap them down, hence the 35thou recommendation.
Bastaad - Do not buy the BPR7ES-11, the "11" is the higher gap'ed plugs from NGK and then you would have to bend the electrode down with your hand gapper, which is not really recommended as the electrode will be tilted down. It is better to get the straight BPR7ES (or order them from NAPA). If you have no luck, I can get you a set and ship them to you. That will be my good deed for the week!
Yasin