Boost is a precious commodity and you don't want to lose any of that horsepower-generating pressurized air to leaks in the system. Even if you're fairly confident that you're pretty air tight, it's still a good idea to double check before getting a tune. With a few parts you may have lying around the garage, find those sneaky boost leaks and make all the power you're supposed to with this El Cheapo DIY boost leak tester! In order to build the right size leak tester, start by measuring the diameter of your turbo inlet. You can identify the inlet side if you see the compressor…