How to improve my laminate screen

S-I-L-V-E-R or RS-MaxxMudd LL sprayed w/HVLP. Bith are great match-ups for a Qumi Q2 , and especially so since you stretching the limits of recommended screen size.

S-I-L-V-E-R is the more dynamic coating of the two, and produces very deep blacks for a higher gain screen. but it has less resistance to ambient light and requires at least 8 very lightly "spray" applied Duster coats with substantial Row overlap (70%) It's among the simplest of mixes, containing only Behr Faux Glaze, Silver Metallic, and water.

RS-MaxxMudd LL is also a higher gain mix, yet it does have a bit more resistance to ambient light than does S-I-L-V-E-R, .....and it features the ability to be rolled if one is good at such. It does require a total of 4 different (purchased) components (Silver - Pearl - UPW - Minwax) so it obviously cost more to assemble.

Curved screens are much harder to execute well and are only necessary to overcome the "pincushion" effect introduced by an anamorphic lens. I would stay with the flat screen.

^This. If you make a curved screen and don't have a lens, you will most likely get barrel distortion, whereby the middle of your screen is taller on the top and bottom than at the edges.