You've had some good advice. Try and find a GT V6 which has been owned by an enthusiast but which hasn't been messed about with. Factory 18" wheels are a must IMHO and if you can find one that's had the Q2 differential and Eibach Anti roll bar fitted, you'll be laughing. I get mid 20's on short journeys and 30+ on a run. Performance will be quicker than the Corrado and about the same as the Golf R32 but I think the engine's power delivery, tractability and most of all, the sound are in a different class. Then you open the bonnet and see that beautiful chromed jewel. Get a good one and you will be in motoring nirvana.
Let us know how you get on.
Current cars : GT 3.2 standard + Q2, 2.0 TS Spider (916). Previous Italian cars: GTV 3.0 P2 (916), 146ti, Spider 2.0 TS (916), 147 2.0 TS, GT Cloverleaf Jtdm, GT Jtdm (crushed by tractor
), Fiat Coupe 16v Turbo, Fiat Coupe 20v Turbo.