Hi, looking for advice on ecu tuning. i have an E39 530d touring and would like to improve driveability/economy (& a bit more grunt would be nice!)
But i'm confused with the apparent choice of going for an expensive remap, tricky chip change or 'plug and play' piggy back device.
These seem to cost about £80, look an easy DIY job and can be removed to restore the car back to original easily but are they any good or just a gimmick?
your experience's/comments would be welcomed. Cheers.