why do people say to go with ngk heat range 7 spark plugs if you're going to boost your itr?

I went to autozone and advance auto to buy plugs and just out of curiosity I had them look up stock 01 itr plug recommendations... they recommend the ngk 7's as well.....

I ended up buying a couple sets of the bkr7e-11's or 1283's... although these are recommended for stock itr's as well..... Shouldn't we be using 8's with boost + itr?

 

I use 8's. NGK of course.. right now I have 10's in there till I can get some more 8's..
My CR is 11:1

 

stock range is 6.. i ran 7's with stock compression.. now running 10:1 (bkre-11 again)

often autozone type places get their information mixed up.