The slight slope on your header rail might be down to a distorted gasket....it's worth checking as you fit it down onto the top of the screen. The fasteners are adjustable as well.
You can get a bit of water coming in at the top of the screen supports. Many of us fit a bit of shaped neoprene there...a DaveW fix! Water can also come up past the side screen support brackets....usually road spray. That's fixable with a touch of neoprene as well....or a more expensive option, inner screen trims from the likes of Allon White or Williams.
