TURBOED-TEG

I smoked my 3rd turbonetic turd *** turbo and went with a Precision Turbo, when I reinstalled the new turbo, I could only hit like 3 psi...what could be the problem? How about a clogged cat, this was causing excess compressor surge and made the bearing fail. So to hit the wg spring (7psi) I am currently running open downpipe, and man it is Loud As ****!! I need a test pipe for the bish...can anyone direct me to a cheap test pipe with a bung in it...right now I have my o2 sensor rigged up at the end of the dp and it hardly ever throws a code...why? I don't know but it does...