hi there mate,
i had a 2stage type switch like that and it was cut into the amal valve wiring which just limited it as it cut the connection to it.
my advice would be to get on the phone to a tuner near you and have a chat with them,but you will need a different chip as the bbr chip will have different settings.get the whole thing set up properly with the correct bits and you will enjoy it!
From my own probs and fun with a 2wd cos is you get a boost controller or air injectors or some thing similar so it doesnt over boost.

hope this helps alittle