So i have an odd issue, i have a 2002 wrx with 122k miles, the only mod it has is a turbo back exhaust(megan down pipe with a HKS hi power exhaust) which i installed a week ago (waiting on the up-pipe/tune/mbc), and the anti fouler mod for the O2 sensor. So when i installed the turbo back exhaust the car sounded great, obnoxiously loud, and it pulled great (over boosted a little with minor fluctuation) i was told this was all normal until i was able to get it properly tuned. So a few days pass and the car is running great, and it had the torque which pulled awesome then i washed my car (got a little water into the exhaust since i was washing the car on a hill and the exhaust hole is massive) i figured that wouldn't be an issue so i left that alone (maybe it is? i thought it was worth mentioning). So i was driving to work in the morning and when getting on the freeway and stepping on the gas i instantly felt the power loss. Felt like my old Mazda, its not terribly slow but there's just no torque behind it. I also noticed my exhaust got quieter, before it sounded like i was on a recon mission in the middle east with the crazy highway drone but now i can actually have a conversation on my phone with someone. As well today my girlfriend noticed the car was terribly slow when getting on the gas. Would anyone happen to know what could cause torque loss and the exhaust to get quieter? The car is holding boost ok, but its not over boosting anymore and still has very minor fluctuation when going WOT.The car idles at 15 vacuum pressure (i read it was supposed to be 20? Boost gauge could be off?).No check engine light. I did a boost leak test and i had no leaks, i cleaned the MAF, and reset the ECU, the spark plugs were changed 1000 miles ago with regular NGK copper plugs, and the fuel filter was changed about 300 miles ago, air filter is brand new, and the turbo inlet hose is new as well. Also using california 91 fuel, and i am not able to datalog. When going WOT there is a loud sucking noise (kinda sounds like an intake) (this was present before the car lost power) and i was told this was normal, its just the down pipe, maybe its not normal? Sounds like air moving. I also have a lot of waste gate flutter during low RPMS (which i figured was normal also). I hope someone could help me out. Thanks in advance.