check on the servicing
for an R youd also want to check if the haldex oil/filter has been changed.
in addition for a manual car (which may have been remapped) think about the clutch , even stg 1 can make them slip. a good quality clutch and fitting isnt cheap
one of the big pluses for DSG can be mapped to accommodate most tuning power levels (clutch clamping load) without changing anything (but if they go bang its even bigger ££)