I have a 99 honda civic si I did a compression test and suspect it has low compression because of misfire?

So the first one came out as.180. Second one 180… Third piston 160… And the last final piston as…180 are my pistons good? Don't mean to sound like a rookie.

They should all be the same… That 3rd piston has something wrong with it… Could be any number of things…
also a misfire does NOT cause low compression… Low compression causes misfires

Misfires are usually caused by spark plugs, plug wires, bad fuel injector, intake manifold leaks, and possibly a bad front 02 sensor. Get it diagnosed if the spark plugs and plug wires don't fix it. Only use NGK or Denso spark plugs.

Valve bad. Head gasket broken ring. Could be lots of things. Do it again after a squirt of oil in each bore. If it's the same it's not the bores. Is it overheating?

You're fine ricer.

You are allowed about a 10% variation between cylinders. Your readings are fine. If you still have a misfire it's not because of compression. If the car has cheap spark plugs that is the first thing I would change. It should have iridium Nipondenso or Bosch spark plugs. DO NOT use Champion as the threads can bind up and strip the plug hole.