Hello,
IMO 125k will be fine for remapping, as long the engine have been checked out 100% prior to the remap. The problems to look for on a 1.8T 20v with 100k+ are, split cracked vac lines, non scaling fpr, boost pipes IC leaks, breather pipes.
We will carry out a fully health check and diagnostics which will be includes in the price, If we are not 100% happy with your engine we wont map it, we will try our best to fix any problem on the day, ie a split vac pipe would be replaced for free on the day if it is going to make the car safe for remapping.
Same with the 530D, these make some really good power and pull like trains after the remap, the only issue with the BMW would be the lower IC pipes popping off but like the golf we will check them out before the remap.
What year is you 530D?
Nick