I've tried the L. lip, it does help, but in my experience, only slightly. Last year the mounting buttons came off mine and it's been sitting in a box ever since, and I've been relying on really good ear plugs, and a relatively quite FF helmet.
From the reading I've done, people who have the best luck with them are under 6 feet tall (I am 6'1"). If I were doing it over, I'd probably skip the lip and get an Aeroflow.
Another thing that does help slightly is to put spacers under windshield's upper mounting holes, which makes the shield a little more upright. If you google around there is a detailed write-up someone in the UK did.