Did they replace the main belt when they did the pulley ?, you might be getting a bit of belt squeal as you are hitting peak torque, the replacement of the tensioner pulley shouldn't require disconnection of anything turbo related as the process can be done from the drivers side wheel well.
My tensioner pulley has just gone as well, I'm getting that awful grinding / rattling sound on idle, the OEM assembly is ridiculously expensive though $229.00, and its sold as a complete replacement part, you cant service the pulley or the bearings independently, a new belt runs in at a pricey $85.00. Although there have been a fair bit of road works near work lately, so I am going to optimistically remove the assembly before buying a new one in the hope that maybe a small rock has jammed itself in there.
Nearly all men can stand adversity. But if you want to test a man's character - give him power.
Abraham Lincoln