regular daily driver. Can I legally swap in California? I want to swap out 6 cylinder for a 4 cylinder head, but if I have to then the complete block. Then drive it regularly without the smog station saying anything. Will I need to switch out harness and ecu blah blah blah?

 

Yes you can swap to a F23/H22 engine. But you will need to use all theF23/H22 emissions components.

 

obviously you can't put a 4 cylinder head on a v6 block, i'm assuming that you misspoke