Starter fluid or propane or brake cleaner are not reliable for testing ffor boost leaks. These methods require strong vacuum; Boost leaks however may cause no boost leak as they may only be leaking at 100kPa/s where your engine's vacuum at idle is only around 15kPa/s. To really test for leaks you need to pressure test the system.
http://www.vfaq.com/mods/ICtester.html
Connect one of these and then pump up to 5 to 10 psi higher than you're normal boost level. If the pressure doesn't hold try putting a second one of these (without the nipple) in the other end of the piping to plug the throttle body side. So, plug with nipple on the turbo input and solid plug on the throttle body side. Then hose everything down with heavily soapy water and watch for bubbles. If you see none and the pressure's staying try another 5psi and you're good.