When I first got this car I saw another at an event somewhere that had a completely stock looking fuel pressure regulator, but when they pulled the vac hose off, it had a hollow set screw in the threads for adjusting it. This was not the kind with an aftermarket top put on it. How was this done? Something I wanted to tinker with and probably waste a 237 regulator I got for free. I am also aware of the socket trick to smash the top down to increase PSI.