according to the ngk site my engine should have bcpr6e-11 plugs in but on the s12 forum they recomend bcpr7es. now what would be the differance ?

nisssan silvia 1.8t ca18det donor engine

Going from 6 to 7 is one grade colder, and the other changes are relatively unimportant. But look it up for yourself onthis site.

many thanks dusty

The colder plug is probably better to use for 'heavy foot syndrome' I went two grades colder in my S13 when I put the bigger turbo on.