if you have already bought them, then you do need to regap them i had massive problems with the ik20's which are specified on the right for my 1.8t but the plugs they were miss firing as soon as the turbo kicked in. i contacted denso about my
problem and they said to regap the plugs but to be honest if it says that they fit then i expect to be modifying them in anyway especially when there such a crucial part of the engine and have ceramic parts in them, eeeeeeasy eeeeeeasy tap tap tap . .. . crack !