the only reason i said 28-46 in your last post was because i didnt know the motor. stock Y7 DX's run 28 psi, up to the C5's, which run 46 psi. like Cronic said, your A6 should run much closer to the 30 psi end of the spectrum. do you have a haynes/chilton manual? they will tell you what the idle regulator/no regulator fuel pressure should be...

anywho, ive heard that AE sells filter-mounted gauges for like $15, so you might want to check on that, just cuz it would be quick and easy. im assuming you have all the vacuum hoses hooked up right?