Cat delete oxygen sensors vs lamda

Ok once again, I know I’m beating this one to death but my exhaust manufacturer has thrown a couple of new options at me.
He suggests on the Brit spec downpipes I should still leave in the bosses for lamda sensors for air fuel mixture control back to the ECU.
My local Jaguar mechanic says if you’re doing the catalytic converters delete with straight pipes and centre box delete I can just delete the bosses for the oxygen sensors as they will have no bearing on ECU and fuel air information.
He also tells me to swap out the stock ECU and buy the Brit spec one as they make the car put out 315 HP compared to our measly 264 HP or whatever the real number is.
I’m a little confused as what is the difference between an oxygen sensor vs a lamda. Are we talking the same thing and do they go into the same exhaust holes in case I want to add a new centre box and cats later?
They also have started to produce the new bigger over the IRS pipes so I’m going all in at this stage.
Tome to put the growl back into the big cat I would say.

“Lambda” is one way to generically describe a closed loop feedback system.

Lambda sensor and oxygen sensor are often used interchangeably.

Removing the oxygen sensors = removing the heart of the feedback system. The ECU will never go into closed loop operation and will remain on the “base” fueling map. Nothing horrible will happen but you’ll probably lose some fuel economy; the base fueling map is a bit on the rich side as I recall.

Changing to a non-Lambda ECU will not give you 315 horsepower


I see no reason whatsoever to delete the O² sensors.
As Doug said, you will lose (more than) some fuel economy , and even responsiveness as the ECU will blindly follow its basic fuel map with no input from the engine.

Even if you delete them though you still don’t need a new ECU as without a signal from the O² sensors it will revert automatically to open loop, i.e. no feedback.
And whatever ECU you use, you will have the exact same number of horses…
What the ECU does is meter the fuel to the air available in the combustion chamber. If no more air or no more compression, no gain whatsoever.
European cars have higher CR.

Your mechanic needs to do some homework me thinks.

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Thank you all, I was thinking along those lines. My mechanic was getting me confused for sure.

The real performance killer is the 4 pre-cats right after the exhaust manifolds. They are very restrictive to flow. Getting rid of the front and rear catalysts lets you go richer so that you can get more power. If you went that rich with catalysts, they would melt down.
Ideal scenario is to have the ECU providing maximum power at about 12.5-13.5:1 and let the Lambda circuit bring it into 15.5:1 range. This helps to make sure you never go lean during transition periods. Then either the low manifold vacuum switch or the full throttle switch can pull the O2 Sensors out of the circuit to give you max power when you need/want it.

I was informed that there is a device to plug the sensors into to fool the computer… anyone know what that’s aboutl