Got a 1991 Cummins intercooled with a 5 speed has 3200 gov springs pump turned way up 140 HP injectors schwitzer turbo (don't know the size) air intake four inch turbo back into five inch stack. Want more power without spending 1000s I have boost and pyro gauges so good there and getting a dual disk clutch so good there. Thanks in advance for any help!

 

what axle gears? taller ratio (numerically lower) might actually help.

 

Its the 3.55 or what ever. Thought about that but I also pull trailers. (20,000 lb) believe it or not so I'd like to not lug it too much more.

 

I retract the ratio change suggestion for 20k# towing

What's your fuel pressure like?

 

I don't exactly but pumps turned up and when its running 30 pounds of boost it will still haze black so its got fuel.