Ok, so here's my dilemma. My rear O2 sensors are shot. I soon plan to upgrade my factory exhaust manifolds for a set of long headers. I plan to leave my catalytic converters in place, however I would like to sometimes be able to unbolt my exhaust and run straight out of my headers without a rear O2 or Catalytic Inefficiency CEL coming on. Is there some way to reprogram the factory computer or some aftermarket computer so that it never checks the rear O2 readings? I know Rover V8s are huge in the engine swap world in the UK, but I seem to have a difficult time finding some parts like these sometimes despite that.

 

What you need is something called an oxygen sensor simulator - if you google it you should find plenty of results, however there may not be any with Rover specific connectors, so you may have to cut and splice.

 

Yes, you can have it reprogrammed to run slightly leaner for a more efficient combustion. I had mine done to run a little leaner and adjust for changed tire size. Got maybe 1mpg improvement according to my UG (probably some hp too but can't prove it). For $120, it'll be worth it in the long run.