I've now sold my car this used to go onto so the unit is up for sale. You simply plug the unit into your OBD port and flash the ECU with the new map. The OEM map is saved back to the unit for future use or if the car goes in for a service, in which case you definetly have to put the original map on! Another good feature of the unit is that you can scan for fault codes. This has saved me a fortune over the years! My car was standard 200BHP, with the map added it increased it to approximately 240BHP, a noticeable difference straight away! The car it was used on was an Audi A4 B7 2005 with the 2.0TFSI engine, petrol. I am aware that other models use this engine so it should work on those too. Please do your research to ascertain if this STS unit is for you. I am unable to advise you, all I will say is that it worked on my car brilliantly. Retail price of this £399. I will accept £275 inc postage via RM Special Delivery. Feel free to PM.