I'm curious as to when the turbo reaches the highest psi of boost? Lets assume an empty bed and no trailer. Is highest boost reached only at WOT? How about normal around-town driving under 2000 rpms?
Thanks.

 

On my truck I need to be heavy on the throttle to see 35-40 p.s.i. Just cruising on the freeway at 75 mph (about 2000 rpm) I'm usually well under 20 psi.

 

Our stock trucks have an electronic wastegate that opens I believe about 28psi. At WOT, my truck will peak at about 33-34psi then drop back to 28 sustained.

At slow speeds your boost will hardly move at all. Climbing a hill or pulling a trailer will increase it obviously. A Boost gauge reading is a good indicator of how much your engine is working at any speed.

Cruising empty at highway speed about 75 mph mine is showing about 6-8 psi. Maybe a little more on hills.

 

It takes the impeller time to spool up in rpm, but boost is made under load. You can see high boost numbers without W.O.T. when simple rolling into the throttle at highway speeds. I've had turbo cars that came with factory boost cutouts that would shut down the spark when the boost spiked and it happened more on the highway than anyplace else. I don't mean standing on it to pass, just pressing in the throttle enough to switch lanes in traffic will put 30+ psi on the guage.

 

At WOT mine will top 40 but everyday driving around town I usually dont top 20. But to answer your question from my personal experience the only time I've seen above 40 lbs is on WOT.