Yep, Mk1 / GD Sport is just a cosmetic job (Mk2 / GE Sport has differences), but the lower profile tyres on the 15" alloys do compromise the ride compared to the 14" wheel. Tyre choice makes quite a difference, the original fit Bridgestone RE040 are quite harsh due the the fairly square shouldered performance oriented profile, other tyres can give a softer ride.
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TG