Yep, and is seems to work really well. I haven't tried it without the check valve yet, but with it, there's no problem building up tank pressure! The only down side I've seen so far is that you MUST release the pressure on the tank after a flight or you'll be leaking fuel all over the place. With the regulator inline, there's something to stop the fuel from being forced into the carb, but without it, there's a slow seepage though the needle valve into the carb.

I theorized that after running the engine for a while, pressure would build up too much in the tank and make the engine run richer, but so far, I haven't seen that happen. But, as I said earlier, I haven't flown it for very long this way, so it could still happen.