2.0 GTI more expensive for me on insurance.
Got my 1.8t for £900 in the end 
I'm only 20 btw
how is that? Its at least three groups lower..
Groups mean nothing really....
All sorts of things are taken into account.
For instance, if a certain make or model of car is involved in accidents more, it's seen as higher risk to insurers, therefor puts insurance up.
Insurance on a Citroen Saxo VTS for me is £3000+ as it's seen as a high risk car even though it's insurance group is lower.
My Mum's 1.5 DCI Nissan Qahqai was circa 2000 for me, yet again my Golf GTI 1.8T is cheaper.
Groups mean nothing, and insurance companies are ****