I have a 1995 12v with 90hp torque plate, 50hp injectors, cold air intake, 4" straight pipe exhaust, boost and exhaust guages, and 450hp clutch. What is the next step in performance? Maybe delivery valves, or is none of this worth doing without a bigger turbo? And how much horsepower can you go to on the stock turbo?

 

get a bigger turbo you dont want to run all that drive pressure created by the stock turbo on the head gasket guys do it but they also have HG problems

 

What do you mean by HG problems?

 

HG is short for Head Gasket. When you start adding more fuel and boost to the engine the cylinder pressures are increased as well. If the cylinder pressure gets too high, the head gasket will blow.
As far as the next mods for your truck i would highly reccomend that you get your timing advanced to about 16* and get a governor spring kit (gsk). 400hp is pushing it on the stock turbo. It can be done but your egts will be quite toasty. Before i thought about adding much more fuel i would start saving $$$ for a turbo upgrade.

 

turn in the WOT screw (Wide open throttle) it has helped me specially on the 160 pumps like yours.

then put in a 4k GSK (4000 rpm governor springs) , that'll wake your truck up!

you can get 'em at piers

 

Yes, I have 3K governor springs from BD, but they're not in the truck yet, and what do you mean by WOT? Just the star wheel in the pump?