Boost solenoid can be removed. The boost sensor sounds like your map sensor it takes a vac source from inlet. T off from inlet for boost gauge, controller and dump valve. Take the wastegate source from the nipple on the turbo. Also Inlet manifold has a cheeky small vac source for the fpr if you haven't already done that.
If its wideband then it's a bung welded in 36~" away from turbo, sits just above 90 degrees to stop moisture damage to the sensor. Mine sits behind the gearbox. You'll need to trail the wires away from moving things drive shafts and steering rack then find your acc live and earth. Job done.
The suspense of waiting for your updates is like waiting for the next episode of eastenders after phil Mitchells gone awoll an it's left on a cliff hanger!! Not that I watch eastenders
Fuel cut is what the FCD removes Sld removes speed limit Or if you want your kmh dials to show in mph and to remove the speed limit you need a mechanical speedo converter that goes between the throttle cable and gearbox
Never had any real issues mate you'll probably find the ones you pay £150 are similar quality the eBay ones have only ever seen them do bulbs never ballasts.
Boost restriction is the boost solenoi needs looping, sld I didnt think would affect engine, an FCD would need a rrfpr to balance the fuelling then setup on a dyno. It's very hard to understand what your saying in a lot of that lol.
With regard to that decat take it off, pop that nut in place and then push the decat so the stud meets the nut, then tighten it that way. If you get me