Going from 1.3 to 1.6 8v .I found a 1.6 with 103,000 miles on it For 500.I need to know if I need to take all the wiring under hood and all under dash from headlights to the radio.Do I need to send Brent the fuse box and all.That is alote of wires in a lot of tit places.Can somebody let me know.

I think I would call Brent

But  a basic  NEED only  write up for  a stripped down harness would be good for folks here  who have no need to worry about emissions testing .

The problem is that without the main parts of the emissions stuff the ECU will adopt a default mode or worse limp mode.

 well nort completely true .
 yes you have to have the basics , O2 , Map , temp , oil . injectors , throttle possition ......and such  as you said , the basicis . but the rest are  open close type units .
 the ecm sends a signal . if it does  not  get one back ,  it  converts .
  most that i have worked with need a ground to return a signal . TBI ecms .
 the  harness i converted on my  4.3  does not  go to fail safe . limp home .
 and it still throws codes if any of the  functional sensors  show something out of spec .
 it only a mater of fooling the ECM to think its getting information back  when infact its not at all

 what inm getting at is that  there is a way .  how many posts do we have on here about sending a harnis off to have it modified .
 how about someone posting what those modifications are . what wires to ground , what sensors are needed . so that a person can set down and  do thier own harness without costing them an additional 250 bucks .
 there is a way if these harnesses are being converted  by companies ..

 the set up that i  have used before , and i know each ecm is diffrent . but  to send off that 4.3 harness  and have it converted to use only basic sensors  was 300.00 .
 i looped it all myself with the help from information on the net . total set up with TBI  from the WY parts was less then 200  and it took me the first tie less the  4 hours to open the harness  , remove the un needed parts  then hook it all up and test it .
I see no reason why this could not be done on  an early suzuki ecm
 the  TBI  setup and harness i took of my  blown 1.6 8v was very basic ..
 i see no reason why  the same harness could not be used on say a 1.3  simply by making an adaptor plate for the 1.6 TBI  and using a injector  close to or for that displacment engine

 im sorry , this probably shouldnt be in the beginner or basic section