for those stock big wheels your going to need that gpm assembly or find a stiffer spring. you can try the spring on the A.E. steering kit i have that kit on my mgt and its very stiff and its a full metal saver setup and turns stock wheels with ease with a 200 OZ servo. i have the jr z9000t 330 oz torque on my nemesis with the saver tightined completely down it will turn the 40 series with ease will standing still. but when i put on stock 55 series it wont the spring always gives on the servo saver. i think the metal saver might be the way to go i wouldnt waist money shoping around trying different springs.