don't try to use the Si engine harness - it is not compatible with the DX chassis harness - you would have to swap in the entire Si chassis harness - you need to use the DX engine harness and do the DPFI to MPFI swap - http://www.geocities.com/teampimports/fuelinj.html
DX knuckles/hubs, mounts and axles are exactly the same as Si.