I did some reading on the 2.5 Valve Cover, yes there is something that VW refers to as a cam splash shield that functions as a baffle making the oily vapor air take a longer route before it gets to the Air/Oil Separator diaphragm area.Ya the stock cover has a baffle in it. If you pull that cover off the underside of the valve cover it is just empty space....
The valve cover used on the TTRS looks like it can be bolted to our engine, and seem to be using the same PCV Diaphragm. I doubt there would be any performance gain, ...but more expensive part to be sure.