Is there some way to control turbo boost. I can only get about 21 lbs and I know people here, with OBS trucks, get better than that with some mods.

I watch the boost gauge climb steadily till it hits about 22 then it seems to drop back a little and settle at 21. tells me I hit a limit someplace.

 

I know I have a 95 PSD which is not a lot different from yours with what seems alot like the same mods as you, at least close to the same mods and I have seen 26 psi boost and she was not acting like she was trying to pull any of that out.

I never saw this much boost till I made the air intake mod either. I put the six position flip switch and the 4" straight pipe and only saw 21 psi boost with the modified stock air box on. I removed this and got me a chromed 4" exhaust 45 degree tip and fit that in place of the long flex hose that went from the air box to the aluminum 4"X3" adapter that hooks to the intake on the turbo.

I didn't like the look of that long flex hose with all the rough surface it has on the inside to get the air tumbling into the turbo.
The long radius 4" chromed 45 degree fitting was just a fit once I used a chop saw to cut off the upset end that is used to slip over fit.

On the other end where the air box was I put me a Wix 46637 air filter and this all set right where the original air box did. All this did the trick for my PSD, as she would pull the boost from then on. I don't know if you have the exhaust like me or the air mods like this or not. I do know though with straight pipe exhaust, no muffler, no cat, and a 3" down pipe, the air mods here, mine will really pull the boost and runs like a raped ape. Hope this might help, have a good morning dude!!!

Just thought I would edit something else in here I just thought of, I have 132K miles on my PSD and she has been maintanced very regular too, if anything maybe too much if such a thing LOL... You know love the truck to death sort of thing LOL...

 

Phydeaux- Something's wrong, buddy. You've got a lot of the same things I do, and I was at 23-24psi boost before I put on the propane. With the propane flowing, I've been over 30psi.
When you installed the Powershot, did it come with a pressure relief valve that goes inline between the boost line to the Powershot, and the MAP sensor? I was thinking you might have installed all the things in the MAP line in the wrong order. You'd want your gauge connection and Powershot connection before the pressure relief valve. The MAP sensor will send a message to the pcm to defuel if it sees 22psi, so the pressure relief valve bleeds off enough boost to fool the MAP sensor, even though the truck is making more.
If you didn't get the valve in your PS2K kit, or mounted it in the wrong place in the MAP line, that would explain your problem.

 

Hey Quad
Just looked at the set up sequence is map sensor ---> relief valve ---> T connector for PS2K ---> T connector for boost gauge. Is that correct.
I figured there was a limit someplace I was hitting, it just acted like that.

 

That's how mine is set up.I'm hitting close to 30psi with my Diesel power chip and LP.