Enhanced Performance in Sussex does this type of remapping on vans and diesel cars with great results apparently. They do it differently though - instead of replacing the chip they give it a diagnostic check I think then as long as the engine is running right they re-write the existing ECU with different settings - also producing more power and better economy. I think they charge around £300. And the original map can be put back at any time if for some reason the customer isn't happy.

A mate of mind had his wife's diesel Mercedes done which upped the HP a lot. He was pissed off that his wife never noticed even though he reckoned it was a lot faster.

Charlie