Ah, two of my top 3 cars right there. I don't know the current trends in the CGT market, but if you can find one you like, get a FGT now as the prices have only been increasing over the last few years with very sharp spike in the last 2-3 months.
Unfortunately can't comment on comparisons with the TT because I only have about 70 miles on the GT since I picked it up last week. Work, family and that pesky thing called sleep keep foiling my plans to take the car out of the garage.
