ok so if i drop a 13b from a S5 into my 81 w/ a 12a, what computers can i get by with, an apexi fuel computer and ignition computer? or what

 

just use a stock S5 ECU and harness??

 

I like Haltech. But you will need to go back to a S4 OMP, not a big deal but just one more thing. Wait, I guess you could get a E11. I belive it has the electric OMP drivers. Check my web site for pictures and a quick wite up

 

if you want to be cheap. hit up a junk yard thre are plenty of N/A second gens. since you cant use the S5 OMP get the S4 OMP, S4 AFM, and the wiring harness and computer out of the S4 as well. then put every thing together.

and you will have the S5 lighter rotors running an S4 comp system. no biggy.

 

i wanted to do it w/o the stock ECU...guess i should mention that

 

oh then go haltech.. its pricey around 800 or so. but it will controle every thing from spark to fuel.