We have been running into quite a few people that have had their twin low pressure return line nipple pumps plumbed incorrectly, which can definitely lead to foaming. Make sure that the lowest nipple / entry point into the reservoir is where you have the return from the steering gear connected to. Getting this backwards can cause headaches. Sometimes we even have a hard time getting the point across, asking the customer to send over some pictures of how the system is plumbed. If you post up a pic or three, I can tell you if you have it right or wrong. Basically, the placement of the second return line nipple is irrelevant to overall pump operations, as you are only exhausting the pressure built up in the brake unit casting every time you let off of the brakes - just a tablespoon or two of fluid, depending upon how hard you apply the brakes. Now the other low pressure return from the steering gear? That's always flowing at a rather high rate, so it is important to get that one right. If you aren't sure, look at some pump images online, seeing where standard non hydroboost low pressure return lines enter the reservoir. This will give you a visual as to which point on your housing is the return nipple for the steering gear. Again, the second auxiliary low pressure nipple placement varies from housing to housing - could be in a lot of different places, but since it is an add on, you should be able to see where the primary return line nipple is. Sometimes if a customer doesn't want to get into all of the discussions, we will simply suggest to test swap the low pressure return lines if a problem seems to exist. If the problem clears up, then it's fixed! If it gets angrier instead, then swap it back...