bad turbo maybe?

[crewcabxlt]

About a week or so ago i noticed my boost gauge was not reading any boost. I dont really know about turbos or even where the gauge hooks up to but i looked under the hood anyway and all i noticed was my air filter had seperated its self from the tubing. Put it back and still no boost on the gauge. Im sorry but i can not tell if the turbo is working for sure or not, i thought it was but now i hear a weird noise.
It sound like its coming through the exhaust. When i rev it up a little i hear a sound like metal spinning on metal. Not at an idle but when reved up to like 1200 and up. It also makes it when driving, but seems to go away if i floor it a little but comes back.

Does this sound like a turbo issue?
Also if it does can i keep driving the truck till i scratch up the coin to replace the turbo ( Ive heard they are spendy)

[crewcabxlt]

I found the tube for the boost guage and it had come loose. There is boost, up to 10lbs when i was getting on it. and it wasnt making the noise so i am thinking it only does it when it warms up maybe?

[madpogue]

Boost gauge is aftermarket.

The noise - is it kind of a whssssh sound? How cold is it where you are? This might just be the EBPV - exhaust back pressure valve - closing in cold weather. Lot of fellas decommission theirs.