Just to give you an idea for me at 26 years old with no ncb, third party on a Mk3 VR6 was £1200 with HIC
a bit high because I'd only held my licence for 18 months or so at the time, and a Mk5 GTI is (I think) a higher ins group anyway... so just being a year older isn't going to help you much!
Just put up with driving around in a 1.2 or something and enjoy paying less road tax

If I'd had a VR6 at 17, with the mentality I had then (and most people I know), I would have died for sure.

Might've managed to be slightly more dead in a Mk5 GTI....