can I lengthen the wire on a factory O2 sensor?
 

I want to start the saab on the factory ecu first then switch to MS. I only have an o2 bung 36" back. Can I lengthen the factory o2 sensor wires with no ill effects?

you should be able to start the car without the o2

I snipped some o2 sensor connectors off something else in the junkyard and built my own extension rather than buying the phenomenally expensive ones when I picked up a used RB header. I've had no issues, just make sure you use proper wire and make good, clean, low resistance solder joints. Damn o2 sensors are super touchy when it comes to voltage drops across connectors or joints.

I believe Ballenger can hook you up with both ends if you are looking to build your own and not deal with the soldering issue. I'd have done that myself but I was in a hurry.