Ok gots some questions about this swap since the k's seem to be alittle more difficult than B swap but heres my question im helping my budd swap a K20z1 in a 2002 civic si and im wondering about the vss issue im using the the original transmission that came in the car..was wondering since im using the stock trans and not the Z1 trans that i dont have to worry about the difference in the VSS sensors K-Pro is a option just dont have funds yet Im using the K20Z1 ecu also so any input would help. also using the EP# wiring harness

 

You can't just swap around ECU's like a b-series. The K20Z1 ECU will not work on the EP3. The plugs and harness are different. You NEED k-pro. Also, it's not ideal to use the 5-speed trans with that swap. The longer gears will cause you to fall out of vtec.

 

^he pretty much nailed it

 

You can still use the k20a3 transmission to get you by. It may work best with a Rsx type s tranny with the gears. I know on my k24a2 my vtec engagement is 3800 rpms so I dont fall out of vtec. But on k20s the vtec crossover is usually higher. Kpro is a must, dont even do the swap without it. Youll waste your time. Also the swaps are no harder than b series , you just need to know about k series first.