I've got a bugeye wrx with exhaust, wheels, spoiler and paying roughly £640. But how much would it increase (rough idea) if I fit bigger injectors, turbo, fuel pump, front mount intercooler and induction kit

 

Hi,

nobody apart from your insurer can really answer that question.

You may find that it is to your advantage to wait until your insurance renewal time to add and disclose the modifications, this may work out more cost effective especially if you are shopping around for quotations.

Ollie
Sky Insurance