The old and new BM100's have a low outlet like that, and it is an internal (in-sump) skimmer.
The old and new BM160's have a high outlet, and it is an external skimmer.
The sump water height would impact back pressure on the outlet tee, but would also provide some pressure to the pump inlet. I bet both of these factors work together to influence the skimmers performance for both water and air throughput.
You would have to do your own plumbing on the BM100 to raise the outlet Tee height, it's height is not adjustable. Closing down the valve on the outlet Tee should have the same impact though as raising the height, more back pressure.
I don't know if there is anyway to simulate more feed side water pressure to the pump on the BM100 though, without raising the sump water level height. You'd have to feed the skimmer pump with another pump, and I think it would get very difficult to control.