Sled pulling turbo

Hey guys, looking for some input on what turbo I should jump to on my sled pulling truck. The trucks a 99 p pump 24 valve cummins, it has a Farrell Diesel 12mm p pump with full cut delivery valves, 5k springs and flows 500cc,timing set at 35° , 6 x .022 injectors, .093 lines, 181-218 cam, lightly ported head, steed speed t4 competition manifold, valve springs, and push rods and the trucks just used for sled pulling only. Usually run between 4,000 and 5,000 rpm down the track.Was running a s475/83 1.0 with the vp and was looking at jumping to a s478/87 1.1 t4 or should i jump to the 96 turbine and maybe a 1.0 or 1.1 t4 exhaust housing? I
don't wanna jump to the 96 and have issues staying on top of it. What do you p pump guys think?

Any class rules to deal with ?

It's a hot stock class with no limitations on the turbo. Most guys run a between a s475 and a s480.

THE 96 will make more power, stainless diesel makes some smaller options for housings on the 96mm t4
auto or manual truck? if auto how much stall