compression test numbers?

[oxbrain]

So I am calling all these junkyards looking for a b6 and they are listing me a compression number. Most are 140-150, but some are as low as 80 or as high as 180. I realised I don't even know what a good compression is, or what that number actually tells me about the engine.
The compression test pumps air into the cylinder and it leaks down to a pressure over time and thats the test number right? So that would mean the piston rings can hold that pressure? Would that tell me if the car leaks or burns oil, knocks, ect.?

[B6T]

B6T's are supposed to be between 135-150psi for a healthy engine. That's with a 7.9:1 compression ratio. I know the B6 has a higher compression ratio, so it's probably supposed to be at least 160psi. I'll check my 323 FSM for you when I get home.

Speaking of compression numbers... with the B6DE head, my compression numbers went from 150-150-145-150psi to 155psi straight across the board.