Sam, It all depends what you want to do with the car. The GT TDi and standard GTi are really better described as GTs - Grand Tourers. The true GTi is the 1.8T and that has the lowered suspension etc. That said, the standard set up with the TDi remains remarkably composed and the added weight over the front wheels assists turn in. Incidentally, are you looking for a GT TDi?? - mine is up for sale.
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1998 UK Golf IV GT TDI
110 bhp plus TuningBox