I reckon such a topic can be usefull to our GTI - leasing addicts.

Here is my (and probably in some cases) your situation..
I want to Tune (remap) my GTI.....for another 40-50 BHP.....software only (DOB= Diagnosis On Board)
If I do it after I receive my car with a state-of-the-art Tuning Company JD-Engineering they charge me 900 euro (sorry you are still in the pound era

)...without letting the lease company know.
BUT BY DOING SO...!!!!...... the factory guarantee is immediately invalid so (for me ) worst case scenario is, if things go wrong with your engine you can be hold responsible for a limited amount of approx. 5500 euro...

.
If you do it by the book...my dealer charges 1400 euro and has the task to inform the lease company who charges you monthly an extra amount
(brakes-tires-fuel)..I do not know how much yet....Although Fuel consumption becomes even less

WHO HAS EXPERIENCE...and what do the charge you.........
,c is