You might want to get the CNC'd center braces as well as the Z-brace (it will stop chassis warping from motor torque) you can usually find them on ebay WAY cheaper than hobbie shops want for them (most places want $50 a piece I got the braces and Z-brace for $30 total off ebay )
And also get a metal geared steering servo I use a Hitec 645MG which cost me under $30 and its working good so far . The stock steering servos pretty crappy IMO I found it not to have smooth movement and was lacking in the torque department.