Turbo PSI ?
 

60 series Detroit, 44,000lbs pulling a medium size hill, what should the turbo psi be reading? Mine use to read 20, now it's been reading 30 psi on the same hill with the same load.

What year? Is it a wastegated turbo?

It's a 2000 T-2000. I don't know what the turbo is. All I do know is that it's pulling like crap.

If it is a 2000, it has a waste gate turbo. That thing is like putting a nozzle on a garden hose.... it does spool up quicker, but it also creates restriction in the exhaust. When I dropped a rebuilt DDEC IV Series 60 in my present truck in August, I had the waste gate turbo removed and replaced with a Borg Warner 171702 non waste gate turbo. Got it for $689 delivered to the house from a dealer listing on Ebay. Prices at local shops won't be much higher. I also put on a turbo blanket from PTP turbo blankets and a ported/coated Bully Dog exhaust manifold. Overall, nice cool EGT's even on tough pulls on a hot day and mid 7 mpg average and will pull a gross load quite well.

It is possible your waste gate is shot. Have it checked out and if it needs replacement, look to a non waste gate version. They are cheaper also.

Is waste gate a brand name? Maybe that is why sometimes when I first take off it sounds like the engine brake is on between gears, when the engine brake is off. The turbo does look like it got very hot at some point. It has a odd color, almost like it went through a fire.

Also, how do you check a turbo? I always thought that when they were bad you got smoke from the exhaust?

No, it is not a brand name. It is a part on some turbochargers.
From the dictionary:
A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. Diversion of exhaust gases regulates the turbine speed, which in turn regulates the rotating speed of the compressor. The primary function of the wastegate is to regulate the maximum boost pressure in turbocharger systems, to protect the engine and the turbocharger. One advantage of installing a remote mount wastegate to a free-float (or non-WG) turbo includes allowance for a smaller A/R turbine housing, resulting in less lag time before the turbo begins to spool and create boost.

I hope this helps. Good luck solving the problem.