What should the boost go up to on a stock 1993, 5.9 with a 5speed.
I'm seeing 19 PSI most in my empty truck.
Is that right.

 

Yep. Between 16-19 on a stock IC'd truck that is not leaking.

 

Sounds spot on.

 

Ok Great Thanks.
Going to do some up grades wanted to have a base line to go from.
To start with
4 inch exhaust, 16mm housing.

 

16mm is not much if any improvement on a 93 which has a 18.5 housing.
16mm on a 92 which is a 22mm housing will be a improvement

4 inch full exhaust is also not much if not a loss with the 16 18.5 or 22mm housings.

The exhaust flows out of the housing to fast ( no pressure ) to keep the compressor side spinning = lag.

Leave the 3" down pipe then open it to 4'' if needed.

 

No pressure is good. All the exhaust goes past the vanes and spins it regardless.

 

Picked up 4 LB of boost with the new 4" Exhaust.

 

Crazy! Google "Project Rust bucket"...I made 301rwhp with mostly stock stuff.