Here's a site i used for reference to make a boost leak tester from $10 of parts from Home Depot: IC Pipe Tester Its for a turbo, but same basic idea.... Note, you will need access to an air compressor tank since once you
pressurize the car , you need to listen carefully for any hissing noises. Also, they said you could use a bike pump on that site, but i tried that once and it was ...