im somewhat ignorant to the whole thing, as i have yet to do a leak-down test, as the equipment for me to do so runs like $400, i have a small compressor, so thats a start. everyone 1st requires a compression test, then if necessary a leak down test, the leak down test will cost you. a good compression tester for example runs about $70-$80. a compression test will tell you what you want at the sametime.