Hi guys,
Wow what a lot of replies! Thanks very much for the advise, I've decided to leave them alone for now. I should have also mentioned that my disco is a Japanese import, quite common here. To be honest I didn't realise that it would make a difference. At present New Zealand sort of has emission testing, it's not actually measured as such, more of a visual thing like the motor is obviously tired and blowing blue smoke. Ditto for diesels but for rich running (black smoke).
I have duly noted the recommendation for NGK plugs. I fitted the Bosch as I remember them being a good brand and didn't want to remortgage the house to buy NGK's! They are a bl**dy silly price here
I will however get some as today it clocked 120K's so time for a oil/filter change.
I must add that this forum is great. Fixed two problems from searching the forums and everyone seems very friendly so I thought a $$ contribution would be in order.
Cheers, James NZ