@Dipesh2031 Im not sure which insurance company your with, im guessing a main stream one, but my company Brent Achre (who specialise in tuned cars) dont charge anymore for coil overs. I mean damn, they only charged me £50 extra when i added 65bhp.
And Wigit is right, Eibach make the VWR springs, they are the exact same just painted in a different colour and £30 more. I think 15% more is a rip off and a waste of cash.
And in regards to drilling your airbox, jeeez....this is VW not a Vauxhall.