Cat exhaust, ok without various sensors?

[Muppet]

I'm going to put an 1100 S engine in my 1100 GS. The exhausts are different so I will use the headers from the S and the Cat silencer and link pipe from the S too. My bike has no cat and no provision for sensors for one, so can I just use the cat silencer and not worry about any sensors? I can't see that it will make any difference.

 

[RickG]

The O2 sensor is there to give the engine management system information about the combustion gas so it can adjust the fuelling to provide close to the 'perfect' air/fuel mix, mostly I think when cruising. If you haven't got a sensor the management system simply provides a mix based on the engine map in it's little brain. No worries so far

If you run a 1100S engine in a 1100GS I would think you need to consider two things:

1) The cat will be slightly more restrictive than an open pipe and therefore, without the feedback from an O2 sensor, you may be running a bit richer than you would like

2) the map in your engine management system set up for a GS and not an S, though I've no idea what differences are. Isn't there something about changing a link in a plug for one of the right type to alter maps between 1100's?