Fueling & Injection - External Pump with Stock tank. Need to vent?

I'm running a MagnaFuel exernal pump on my 99 SS. I'm using my stock tank. I installed a bulkhead fitting on the lower driverside of the tank for the supply line. Do I need to add a vent or is the tank already vented? I had a custom aluminum plate made to replace the stock pump housing. This is where my return line is connected.

Thanks
Chris