Mine leaks at the front corners and rear corners. If washing, I think it leaks at the sides too from the spray coming at it from the sides. For the price I expected it to outperform my $100 amazon cover I had on my Tundra.
I have an F1 cover and the little it does leak goes down the sides or g ET s funneled into the drain tubes. My bed mat keeps my cargo dry enough and I have a bed bag if it has to be waterproof. The fit of the cover is finicky so I’m not sure if adding a seal would let it close properly. The quality isn’t a high as before Real Truck took over Bakflip. I would have paid more for better fit and materials.