Hi-Donald If the oxygen sensor on the original part is still in good working condition, you can still use it. If not, you have to order an upstream/before/front location oxygen sensor. The automotive shop would run a diagnostic on your car and a code should indicate if the front or rear oxygen sensor is already bad.

Donald, My upstream o2 sensor was located on the exhaust manifold facing the front of the vehicle. The downstream was located right after the cat on the midpipe. There is no location for the sensor on the cat itself. If you changed exhaust manifolds and do not have a location for an upstream o2 sensor a hole can be cut and a bung can be welded in. The upstream can technically go anywhere before the cat if this is the case. Hope this helps and good luck! -J

Hi Jan, it is my pleasure to assist you. Yes, we do have the California-approved converter for this group of vehicles. Click on the link below to see and place an order today for 5% less than the usual price while supplies last. I'm hoping this is useful. Enjoy your online shopping at CarParts.com! https://www.carparts.com/details/Mazda/Miata/Magnaflow/Catalytic_Converter/2000/LS/4_Cyl_1-dot-8L/M66452992.html?can=CPGG4850_CSQA_20220819

H Steve, I'm glad to be of help to you. Yes, we do have the direct-fit catalytic converters for the 1997 Mazda Miata. Make sure to verify that a part complies with emission control requirements by examining the Vehicle Emission Control Information sticker, which is typically located underneath the hood. Click on the link below to choose among the options we have available and order at a discounted price while supplies last. I hope this is helpful. At CarParts.com, have fun buying! https://www.carparts.com/search?q=Catalytic_Converter&vehicle[model]=Miata&vehicle[make]=Mazda&vehicle[year]=1997&filters[universal]=false&can=CPGG4850_CSQA_20220817