Oxygen sensor wiring

[Geoffro]

Pretty sure you can just extend the wires, just make sure you match the colours.

[manga_blue]

Best to stick as close as you can to original length. I really can't understand at all why but matching lengths exactly is often part of the fitting directions.

[Steampunk]

I can only assume that the factory is pedantic about wire lengths because of the difference in resistance the longer/shorter you go which would give difference readings....?

This might help:

http://mymiata.paladinmicro.com/Miata4-WireO2.htm

I am suspicious as to why SP Motorsport would make the O2 sensor plug too far out of reach. Even the el-cheapo ones on fleebay are located correctly.

[Garry]

When Mazda Motorsport built the SP the O2 sensor must be a bit closer to the engine than in a NA car because there is about 200mm to much wire that they just attached to the valve cover. I'm not sure if this was to keep the wire the same length as the NA version for resistance reasons or they were just to tight to make up a special O2 sensor for the SP. It always looked bodge to me.

If you need to extend the wires you will need to use crimp connectors as the wire is made of something other than copper and the solder wont stick to it.

[Steampunk]

Gaskets are surprisingly expensive, lucky you don't have to buy a manifold gasket.
I bought mine from Autobarn. The gasket for the cat-to-pipe was around $8 ... ? (manifold gaskets go up to $120!)
Ring the usual suspects and get the cheapest price.

If you are certain it's a bolt-on then you can try it yourself, and spray the bolts with plenty of WD-40 or Lanolin lube to help free it. If you have anti-seize grease, then it's a good idea to spread some on the bolts when you reinstall it.
Shouldn't be too difficult though, it's all about leverage ;)