Nothing but some welding skilz
I pretty sure the SIR mounts that come with it will bolt directly in to the casis. (I was told this by EXP swapers) Im not sure if thats for Just the SI's or not. But if you have to you could buy some HAsport or placeRacing mounts... It would be cheaper/better if you just moved the mounts on you chasis, then again not everyone knows how to mig weld.