2004 GTP Spark Plug Question (KR)

2004 GTP w/ 3.4" pulley, 180 tstat, CAI, SLP Exhaust. NOW NEED PLUGS. Called zzperformance and they recommeneded NGK TR7IX's (2.5 heat ranges colder) but they sent me the TR6IX's. I installed the TR6IX's and am just looking to make the car reliable (not totally eliminate KR, just make the ping managable for the ecm). When I pulled the stock plugs, yup, they were black, shiny, burned. Anyone have experience with the 2004's? Should I stick with the 6's or go with the 7's and risk them fouling? I need to drive this car cross country in a couple of weeks. Thanks!