for springs.. we still running 4dot up front.. 3 dot rear.. when its smooth high bite.. we went to 4dot rears.. i did use mugen springs last year.. they work.. but you have to flip the spring collar because the mugen springs are smaller diameter.. the kyosho springs work as well.. at nats this year.. the AE guys were borrowing the xray springs and swaybars.. just a little info..