I have a 238* @0.050" 110* LSA 0.474" lift cam. Don't know how it's installed, though.
The weather today is truly horrible so I'm not sure I'll be going outside to remove the grate but maybe I'll push myself.
I think you're right, just slipping a couple of feet of wider solid ducting over the tailpipes will allow the pressure puffs to escape and the net flow of gases will still pull all the exhaust out the right way. I'll try that.