Will the multi port fuel injected intake manifold from the 1.6l engine fit onto the 1.5 without major modifications? if so does it require a ECM swap?
i know the MPFI has better fuel efficiency and im wanting to get more miles per tank outta my car.

i've got an 89 hatch 5spd with a 1.5l sohc no mods

 

if you have no internal mods it will be pointless save yourself time and money
the motor is a vacum it only suck so much air putting a larger bore throtle body
will help throtle response but too much work for little profit get a good air filter
for better gas mileage

 

the manifold will fit,but it will require wiring your car for multi-point injection,along with the proper ECU.http://tech.hybridgarage.com/t...g.htm this will give you an idea of the wiring.
if your main concern is fuel mileage,i'd leave it alone.i don't think you'll gain any mileage with the multi-point,and if you do,it won't be enough to justify the work and cost.
chris