Robertio

Not recommended unless you have a good idea of how to map and the appropriate extra hardware (wideband, EGT monitoring, etc.). I've mapped quite a few cars, and like CPH have seen some interesting maps (and wondered why the cars hadn't blown up yet).

Even when you know what you are doing you can't instantly do another kind of car as lots have their own individual strange requirements - ie certain rpm range that has to be rich, or a limit on a standard component (JTD gearbox for instance) that you only find out from those that have got the t-shirt, or by breaking it yourself.