I built a Saab 2.3 engine with a large Vgt turbo from a dodge ram , no heat issues even at 2 bar 500+ hp . Controlling the vane is the hard bit . Needs to be open on cruise \light throttle then close when boost is requested to spool fast whilst opening back up as pressure and flow rise , a lot use a simple spring to hold the vane closed and let turbine inlet pressure push the vanes open but as soon as you lift and lose pressure the vane shuts you lose a lot of turbine speed as the holset had a speed sensor .
