I'm going thru the process of testing various NGK plugs
My Plugs
6's (el cheapo)
7's (stock plug for my S)
8's (irridum - stock plug for Cup car??)
Tried the 6's, they seemed ok, can't see any issues on the plugs after 1000 miles, pistons looked good (scope).
Just put the 7's in and am testing now.
Will put the 8's in for Track.
Anyone's opinions on the 6's (ignore box label they are not 7's, used just for cylinder labels 1,2,3,4)??
Cheers, Rob.