I have a liquid filled BBK mounted on my fuel rail. I unscrewed the shrader valve and theaded in a 45% elbow and a coupler to the gauge. It works great but it's almost in the way. If I'm tightening the collar nut and my wrench slips the gauge is doomed. So far, so good. If I need to uncouple the fuel line I just wait until the gauge reads 0. You can also get a gauge with a shrader valve chuck that you can plug onto it and read the pressure whenever you want. Well, not going down the highway but the rail mount won't help you there either.