Hi Bill,
Yes, a colder plug is called for on the 2000 SVT. Presumably due to the higher compression. Some have posted here that using the same plug as the other V6 Contours works just fine. A few have even posted having problems with the colder plug. Conventional wisdom here seems to be that the standard heat range is fine even on somewhat modified engines and the colder plug not deeded or desired unless it is heavily modified.