I've decided I want twins, but I have not decided on which set up. I plan on o-ringing and porting my head, installing a helix 2 cam and f-1 valve springs, after that I will put on tiwns, but I dont know whether to put a k-31 on bottom or a s-400. I tow alot, the most I tow is a flat bed trailer with hay loaded weighin about 19,000 pounds. How much power will a phat shaft 62/k-31 set up support vs a phat shaft 62/s-400? Thanks for the help guys.

 

Before my last pump mods my truck with mach 1.2 injectors, SPS62/k31 was 480hp, SPS62/S400 was 522. No changes except turbo. The k31 pulls stronger on the bottom end and tows better.