I recently had my Forester engine serviced and afterwards it didn't feel like I was getting boost and was getting a whirring/spinning noise while throttling. I brought it back and they realized they left some loose turbo vacuum hoses. They put them back on and it's not making the noises anymore but I think it still doesn't feel like there's a lot of boost - at least not like before. They test drove it with me and say it does feel like there's some boost at the high end, but I certainly am not feeling the boost when I'm merging on the highway or hitting the throttle.
At this point, it's just seat of butt testing to know what's going on - is there a more definitive way I can diagnose whether I'm getting the proper turbo boost - or at least that the turbo boost is working at all - as a non-mechanic? Something I can point at and say yes/no it is working before I take it back to the mechanic?