How on earth did this air compressor keep going

My Tu-Flo 750 air compressor was fluctuating between 90 - 150 psi on long upgrades. Turns out the unloaders were heavily carboned up and barely working. The compressor supply comes from between the turbocharger and the aftercooler where it gets hot air especially when the engine is working hard.
The turbo disintegrated a couple of years ago, and although I cleaned out the aftercooler, I didn't touch the compressor. This is the result. Now I am about to plumb the supply line between the air cleaners and turbo, turns out the air intake on my KW already has a boss welded on and blanked off just for this.
Why they didn't do this from new is beyond me. I was talking to a CAT mechanic of 30 years experience, and apparently about half the CAT engines they see have the intake after the turbo, and the other half before the turbo. Mine is a 3408.
See the new and old unloaders here. You wont believe they were still working, if only just.

http://imgur.com/a/7edBJ

 

What air dryer lol

 

I've heard about this valve, a friend of mine has got one on his 3408. Do you know the part # or correct name for it and is there a CAT part # for it so I can search the CAT SIS Partstore?
I actually bought that little air filter you're talking about a while ago but it won't fit because the compressor is on an angle. I was thinking of remote mounting it but everyone I know has gone the way of plumbing the compressor supply between the turbo and air filters.

 

Thanks. Found it. I'll do a search later to see if CAT stock it