Hey guys, New here. Excuse me if I'm repeating. I have a 2014 WRX hatchback. I'll make this short. 2021 I blew a rod. Had an extended warranty, thank god. Subaru rebuilt my top end, with a "new" turbo. Quotations on the "new" turbo, cause I was talking to Cobb and the guy said Subaru doesn't replace your turbos with a new turbo, they use old parts. Can't confirm this. After I got my car back, I had left to Israel for work, for 3 years. Car had sat, with occasional start up and maintenance. I have a Cobb AP, and Cobb Intake. Everything else is bone stock. I returned from Israel to Idaho, my WRX was running fine. But not hitting my target, I'm having a problem hitting my boost target, should be up near 17 PSI. I closes I got was around 15.89 PSI. Eventually, my PSI is getting lower and lower, down to 13.89 PSI. I logged data, sent to Cobb, they said I most likely have a boost leak. I replaced my TBIC hose, with a Mishimoto. As he recommended. Still hitting 13.89 PSI! I took my car in for a boost leak test. They found nothing. Everything looks perfect. They said maybe a "tired" turbo. Makes sense, but wanting to get some feedback from you guys.

What could it be? Thanks in advance!