I got the NGKTR5's with my procharger kit and thats what im running now. The NGKTR5's are standard heat range copper Vpower plug for high performance. I was wondering if I could run the NGKTR6's? Those are a single heat range "Colder" Vpower plug for hi -boost & NOS applications. Now Im not running hi boost but I am running some. Could I run the tr6s with out any troubles? Would the car haft to be retuned? If so I'll just get the tr5's again. I got about 1000 more miles on the tr5's untill they need to be changed.