OK. It seems like my car has a exhaust/boost leak somewhere. I've installed UP about a month ago and it's been fine for like 3 weeks. Last week I started getting slight hesitations and now I get very noticeable hesitations when I accelerate. Oh ya peak boost also came down too. from .11 to .1. Also around 0psi I hear a very loud leaking sound hehe I dunno if turbo sounds this loud but it goes away when the boost goes up. I've also installed a Y pipe since then. Do I have to reinstall Up??????
I have had problems with the EGT plug in the side of the uppipe coming out. I just screwed it back in. If you have your stock intake removed, you can just stick your hand down there and see if it is still screwed in. It doesn't thread the greatest, but if you get it pretty tight it will stay. You can also have someone rev your engine while you stick your head under the hood for the sound. When my EGT plug came out I got a CEL, you may or may not get one.
I just replied in the other leak thread about just getting the WRX exhaust/intake diagram from scoobymods and following it through your car to check for all connections. That is the best option right now besides having someone rev the car for you.
http://www.serianni.net/images/wrx-intake-exhaust-diagram.gif. I would say go around and pull on stuff. Nothing should just come apart. You can see obvious things like a loose hose clamp on your turbo to ypipe. You should also start your car and rev it by moving the throttle body cables. If its an exhaust leak listen for where the car sounds like harley. If its an intake leak, you should hear a hissing sound from one of the connections. Lastly, you could put like baby powder near somewhere you think you could have a leak, and if it gets blown away then there is a leak near there.