I use my compression tester only to check cylinder pressure's, but my leakdown shows leakage at the valves or rings or sometimes head gaskets, on a side note, after 6 years of beating on my 350, my cylinders leakdown
3% @ 100psi.
How much to do a comp test, leak down and boost leak?.....We have a comp tester and a leak down. The compression tester will show 99% of problems. The leak down tester just helps pinpoint. If there is a problem the motor needs to come apart anyway, so the leak down test is kind of pointless. We do visual diagnostics for free and can do a comp/leak down if needed.