There can be that puddling problem with the wet kit, and that can cause intake backfires. I had the dry kit on my LS. The other advantage of dry over wet is that you can place the nozzle farther away from the throttle body, and get a better mixture of nitrous with the intake air. With the wet kit, the nozzle has to be as close to the throttle body as you can get it. As far as how the dry kit adds fuel, the ECU doesn't tell it it needs more fuel. The zex nitrous unit adds fuel pressure based on the nitrous pressure, which causes more fuel to spray out of the injectors. The only wet kit I would ever run is a direct port kit.

Dry kit is better than single fogger wet.