I actually have the same system and love it. Note that overarm dust collection on a table saw - just by virtue of the cuts being made and the general physics of the cut, (the blade rotation is throwing dust away/ back, which is your DC is trying to overcome by collecting from the above), will likely never be perfect - in my opinion, it's a function of an overarm DC hood being "significantly better" than not using anything at all, and the Shark Guard is as good/ better than most others that I've seen/ tried there.
That said - how large is the dust port on your guard? The standard 2.5" (shop vac) port is a little weak, just by virtue of the air movement allowed through the smaller port. I have a 3" on mine, and find that to be the best compromise - I had a 4" port installed initially, but the suction coming out of it was actually too much - enough to lift small/ thin pieces off of the table, so I run the 3" now w/ good results. YMMV. Good luck!