I've got one and I'm very happy with it. Works out cheaper in the long run as Dave's rolling road time is very cheap and I'm constantly changing spec. It's also handy in a light car to have it mapped without a big boost spike, but as said any custom map can do this. It's got some handy gadgets - switchable maps, in gear boost adjustment, coilpack. Not plug and play on a cossie, but fine on my Dax where everything is bespoke anyway.