Am I seeing that picture right, that the piping from the compressor is routed first between the turbo and the exhaust manifold, and then hugs the turbine section and runs right next to the exhaust for a few more inches? It would be ironic if that IC piping is transferring as much heat into the air as the intercooler is removing.

You normally can't hear your BOV by blipping the throttle unless you have a load so you can build boost. *however* if you do not have a load (like the car is just sitting in neutral) and keep the RPMs up high enough so that the turbo spools up, and quickly close the throttle body plate, that momentarily builds up pressure and the BOV will sound