I had a mild re-map done on my Octavia 110 tdi about 18k miles ago, took it to 143bhp, with a hefty increase in torque.

Economy is very much dependant on how you drive, but im still getting 50-55mpg regardless of how hard or easy i am with it.

No noticable increase in smoke on acceleration, and more importantly, it flew through the smoke test on the MOT.

Best value for money mod ive EVER done to a car.