Wrong

Edit: Just realised I left this on a cliff hanger! Just take your downpipe, decat section w/e to a local exhaust place and they should be able to weld in a new bung for you. You can run your car without an o2 sensor (afterall this is what happens when it is being mapped). But for decent fuel economy (helpfull when driving to Germany you could do with it). I can't see why it would stop the car from starting though as you would be running open loop on cold-starts.