X2
the D15B2 and the Si D16A6 use the same head - the Si just has a better camshaft - assuming you would be converting from DPFI to MPFI, you would end up somewhere between the 92hp D15B2 and the 108hp D16A6 - split the difference and you would be around 100hp
a lot of work to swap heads when you could just swap the camshafts and do the DPFI to MPFI changes and have the same thing