I disagree with the conclusion on that thread
1) Exhaust brake will cause head gasket failure. Huh? Exhaust brake is 35 psi. Compression is 400+ psi. Might cause exhaust manifold gasket or turbo seal failure but not head gasket. Incidentally the turbo is going to give you 10-15 psi of back pressure (under max boost) anyway, so we already know it can take that pressure.
2) Exhaust brake cause piston damage. Again, ***??? Having exhaust brake on at full throttle sure, but at idle going downhill? Hardly. There's minimal fuel injection, so where's the heat coming from????
All the exhaust brake does is restrict the exhaust so the engine acts like an air pump and absorbs power compressing the exhaust. No combustion, no heat, no excessive pressure.
The only thing to be concerned about on the IDI is the high manifold pressure causing the exhaust valves to float and hit the pistons. This is why the 35 psi brake is used and not the 50 psi one. Also a very easy thing to fix, just upgrade the valve springs.