8.3 Cummins performance

1994 F800 with a 240 HP 8.3 Cummins. Has a P-pump, 58mm HX40, air to air intercooler, and stock as a rock. Looking to get a little more pep, maybe 325 to 350 HP. This thing weighs between 16K and 20K on an average day hurtling down the road at 70 MPH plus. Occasionally tows 25K behind it.

I think I can get enough fuel as is to get to a solid 325 HP. What do I need to do for air? I presume an S400 frame turbo? It has a T4 foot...

What size turbo would work well? It is a manual so spool up is important (and could use improvement over the stock 18CM housing).

S468? S471? What hot side?

Thanks

Look at the fl60 mutt thread on here, I think he went s366. How about a big turbine s364sxe with a .91 or .83? What is your average rpm range? What is the steady state cruise rpm on the highway?

That hx40 might surprise you. Add the fuel and run it. A t4 s366 would my turbo of choice if the exhaust gets too hot.

IIO. Here for knowledge.