you need a boost gauge mate, if it runs over 10 psi then its chipped, if its not chipped then it will cut out at 10.5 psi, normally if u open the ecu, one of the long chips inside will proberly have something written on it, or a sticker on it if its chipped.

That switch thing is strange, only thing i can think of is that some people has a switch on their dash which disables the power to the amal valve which cuts your boost. perhaps something there?, or a dodgy amal valve, disconnect it and put in a bleed valve