EGT doesn't matter on a 6.5 like it does on a Cummins. I have attempted to get a 6.2 with uncoated pistons to I TRIED TO BY-PASS THE CUSSING FILTER melted pistons out the exhaust and sustained 1550 EGT towing during said attempts. All it did was give me heartburn and turn the turbo blanket black. 6.5's have coated piston tops and that helps engine oil live to the 2500 mile change interval. So EGT was not a concern that I watched.
If you look at the diverter valve itself you see the "angle" it is at. This angle diverts 1/2 the manifold into the smaller wheel section of the turbo. IMO it would be fine in a devided manifold, but, it may need more room for decent exhaust flow. Just saying the valve doesn't block. Doesn't mean it's a recommend configuration.
This brings up install orentation. It has to be mounted to divert away from the larger part of the wheel. So it would keep heat away from the center section in theroy. I had to move AC lines and coolant surge tank as I could not spin the BD 180 degrees and have it work.
In practice keep in mind this was designed for a Cummins and 'we' threw it on 6.2/6.5's without piston oil squirters, piston coolers. I ruined, via overheating, conventional engine oil as exhaust restrictions keep heat in the engine. Synthetic was able to take the heat. Yeah drive pressure goes up when closed. The large turbo I was using had a 1:1.1 drive pressure ratio. Way better than factory. Did not measure BD valve, but, when open it would be the 1:1.1.
Once you build boost the valve opens up and is more or less out of the way. What boost do you have at 70 MPH cruise now? This will tell you if the valve would be open or not.