If you have some screws that won't come all the way out, you can wrap a small amount of masking tape under the head of the screw to hold it up so that the threads don't drop down and engage the threads in the head while you are trying to pop the cover loose.
You can pry between the head and the valve cover as long as you keep your pry bar outside of the gasket sealing surface. You can see where the raised gasket stands proud of the valve cover which leaves ~2 mm gap between the head and plastic valve cover. As long as you don't mar the head where the gasket makes contact, you are ok.
In the image below, on the upper left corner of the photo, which is actually near the oil filter housing, you can see the gasket runs in that groove inside that upper corner screw. This is where you can get some leverage with a pry bar wedged between the valve cover and head.
Also, I count 31 screws holding the valve cover down, not 28.
A key point: DON'T FORGET TO REMOVE THE THREE (3) GROUND STUDS NEAR THE MIDDLE OF THE VALVE COVER THAT SERVE AS THE GROUNDING POINT FOR THE FUEL INJECTORS. This is where you need an extra deep 10mm socket to reach over the top of the grounding stud. Even with a deep socket, you still may not be able to fully insert your 3/8" ratchet into the end of the socket and still engage the 10 mm hex nut down at the face of the cover. This is ok because not much torque is required to remove/install the grounding studs.
