The 366 spring allows the pump to fuel all the way to 3200 RPM. Stock starts defueling at around 26-2800 RPM, so it's a big improvment. It also makes the throttle a lot touchier. Very good upgrade, and it oly costs about $18.
A good towing set up, that will be around 350rwhp would be...
370's
Super HX40
Piston Lift Pump
Good Converter or Clutch
BHAF
4" Exhaust
Mild Pump Tweaks
366 Spring