Not sure of your exact setup, but it sounds (and looks on your profile) like you have the 2nd gen setup. Do you have the 2nd gen ecu and cylinder head?
If so, you will not be running a map sensor, only an air flow meter (which i could see in one of your pics).
In terms of the boost cut, the tvsv is not linked to a map sensor, but a turbo pressure sensor, and is only active in 3rd, 4th & 5th gear. It's basically a open or closed valve which when open bleeds off about 3psi from the actuator. If you're running a boost controller, you should really block the vsv off as strictly speaking you have 2 controllers fighting each other for control. You might find that this results in boost spikes which are causing the over boost and fule cut. Try blocking the vsv off first by blocking both the pipe on the actuator and the pipe running to the vsv. This will also allow full boost in all gears.
Failing that, you can install a boost cut defencer which can be made quite easily which will mask the reading from the turbo pressure sensor so that you can run higher boost. Don't run more than 14PSI though unless you have a metal head gasket, otherwise it will fail fairly quickly.
Details on the vsv and how to block it off, and also how to make a Fuel cut defencer are on this website along with loads of other really useful info.
www.gtfours.co.ukHope that helps
Chris