you can put an LS in a miata and still get it to pass smog here in California. We've done lots of conversions that get referee certification. You just have to have all the smog equipment from the original donor attached. A little more fabrication work, but we've done it. We just finished an LS swapped Chevrolet S10. From 2001. It gets smogged like normal from here on out.. it just has a V8 in it.
