You would need a bigger line from the room to the bay, and like Earl said it will drop out of foam on its way. I've seen a number of washes built in the 80's that were like that, and you really can't get a good consistent low pressure spray or foam at the brush unless the run is fairly short. I used to manage a chain of washes (I think there were eleven) that had the foam brush generators in the room with a 1/2" hose going to the bay. If I adjusted to make good foam, the farthest bays took a couple minutes to start. If I adjusted to get the foam to the bay quickly, it would spit and sputter or pause for a period before spitting out another cough of overly dry foam. I tried smaller hose but it just restricted the foam even worse. I eventually started replacing the hose as I needed to with a pair of 1/4" tubing lines and it worked great.