ngk = bpr6e stock code 6464
ive got some bosch super plus wrdc9's which i can't bloody get in cos the old un's won't come out yet!!!
your friendly motor factors will help you, they vary in price up to about £80 a set for lpg plugs although there is debate as to whether these make a difference,
also change the leads, in my opinion they should come as a duo and you shouldn't change one without the other, finances and circumstances permitting of course.
if the motor factor can't tell you which plug it is then do not buy from them, even halfors will tell you which plugs they stock for em!!!
when they say what number id the rr you want to wonder who the expert is here!!!
hth
ps the websites of most plug manufacturers have a part finder on em!!