1) Is the NGK BKR5EIX-11 the correct plug for my 2004 Crossfire? It is listed for the 2004 SLK320, nobody has listings for the Crossfire (I have had fantastic service from these NGK Iridium's in a 2-stroke dirtbike).

2) Assuming that this is the correct model plug, what about the heat range? The "5" heat range is what is called for as stock on the SLK320 everywhere I look except Needswings lists one step colder at "6" as the correct stock range and offers "7" as one step colder. What do you all use on stock daily driver cars?

Thanks in advance for the help, I tried the "search" here, and read a lot of threads, but I could not find the answers i needed.