I didn't brace with anything. Mine lay's pretty tight to the engine and some hoses and the corner of the filter sits against the inside of the wheel well. At first I was worried it might move or vibrate loose, but it hasent budged at all.
I toyed with the idea of just wrapping some hanger strap and bolting it to any hole on the frame.
Mods: Thule Xsporter 422XT bed rack, Underrail Rhinolining, MOPAR class IV Hitch, DIY CAI, Aero Turbine 3030.
Future Mods/Wishlist: Tuner, Daystar Comfort Ride 1.5" Leveling kit, Nerf Bars, Police style push bumper with light guards, KC or Thule trail lights, HID projector lights.