I fooled around with a few boost leak tester ideas. For a variety of reasons, I liked testing by inflating at the hose from the turbo to the passenger side intercooler. With the motor turned off the throttle plate is shut so you are only pressurizing the boost circuit: nothing else.

This might cost $12.00, I think that's what I spent. Here's what you need.



The 1 1/2" PCV pipe is the perfect size for the hose coming out of the bottom of the turbo. You can get Schrader valves at any auto parts store.

Start by drilling a hole in the 1 1/2"cap for your valve.



Don't know that you have to do this, but I put lots of silicon adhesive around the hole, then put the valve in and let it dry for 24 hours.



Then cut the PCV to size so that about a 1/2" will stick out of the cap. Use PCV glue and turn as you insert the PCV. You end up with your boost leak test tool.



Then just remove the boost hose from the bottom of the turbo and crank down on the clamp to hold the test tool in against the pressure you're about to add. Be careful. Remove that oil fill cap first in case boost leaks into the crank case. You do not want to pressurize your seals. A bicycle tire pump will take a lot of pumping, but even one of those little electric tire pumps will get you some pressure. My APR Stage 1 asks for about 17 psi of boost, so that's all the pressure I used here. You can hear a leak. It's a hissing sound. Mine was in the clamp on the hose between the driver's side intercooler and the throttle body.