you are aware that the cylinders see over 700 psi of pressure during normal use right?? This does not damage the engine at all, its a safe procedure as long as you don't blow the plastic pipes to pieces. Which of course we aren't gonna go that far.
Its common practice to pressurize the pipes (yes on the engine with it off) to see where you have boost leaks.
*edit* i might have mis-interpreted your post, but I'm not literally blowing the pipes apart, I just want to see where they leak, and at what boost.