I moved from a 110 hp MK1 to a 105 hp MK2 and whilst I usually drive slowly for economy on the couple of occasions on a long overtake the 5hp less working against a significantly heavier vehicle has been noticeable so I have been looking into a basic remap only, no turbos or intercoolers etc.   Hard to find prices but I get the impression to go to a tuning company for a reflash of the ECU is likely to cost around £300 and there is the logistic problem of me being in France.