just a thought, bought new plugs the other day and all they had in stock was the ngk 7b's, (stupildy i bought them anyway) my car is standard my00 scoob, it seemed to run great on these at first but after say 20mins of hard driving itd oesnt seem to want to boost higher up the gears i.e 4th and fifth, would this be down to the plugs? (i think there suposed to be ran in standard on 6b's?)
im planning on a decat and boost controler anyway so if this is the problem it shouldn't be for long

 

changing from 6's to 7's shouldn't be an issue

 

people upgrade to 7s to run higher boost.

 

Did you gap them properly?

It is critical on these engines & will cause problems if they are not set to 0.7mm

 

i know they used for higher boost etc so thats why i thought since mine is standard it might cause it to not run right, it said sumthing about not gapping them on the box i got them in, so i just left them ( to be honest im noit quite sure what gapping them is)

 

I'm sure my 7's were pre-gapped to 0.7mm out of the box? Maybe wrong though.