just bought a 89 hatch for a daily driver and was wondering if i could get a 88-89 si harness, dizzy, intake manifold..etc and convert it to mpfi...would the harness just plug right in?

 

yes if you have the harness and the parts, it is plug and play

 

It may be plug and play but it WILL NOT work. if yours isnt MPFI to begin with, you can't just drop a mpfi harness into it. The interior harness doesnt have the wires within it to function with mpfi. You would have to swap the interior harness to an Si as well for it to work as a direct drop in. otherwise you have to take your dpfi harness and convert it to run mpfi.