I’m going to start the process of sorting a secondary CAT delete for my S1.

I just need more noise.

Has anyone done this?

I’m hoping it doesn’t set off a light on the dash for emission readings.

I’ve performed a secondary CAT delete on a V12 car I have with no adverse effects

Is there room for a cat bypass.

Can you get access to details of the ecu data management?
I have a Rover Gems Plus8. The system monitors exhaust and has two O2 sensors for each cat. Upstream and downstream
Basically The upstream measures emissions and downstream post cat to indicate cat performance/ failure. It has heated sensors and monitors the heating too. I did have a post cat heater fault trigger the MIL but cleaning contacts sorted it. I have an Autel Maxiscan OBD unit that can delete minor detected faults and also check running data. It covers O2 sensors amongst the many other parameters.
Some systems can be “fooled” to compensate, I think a lot of the plug in chip devices do this by modifying signals.
There should be some aero experts who can-advise.
One point to watch is MOT. If you remove a cat then it is an auto fail just from a visual. Maybe a cat divert would be better? Some cars have that as a standard. Putting the car into a spirts mode triggers a divert valve or similar.

Hi Viper. I had sports cats on mine and removed them a few years ago because the nuts were nearly rusted through and gave them a coat of zinc oxide paint. The boy in me couldnt resist staring the engine it sounded bonkers quite frankly and the ecu light came on immediately. After re assembly and the cats fitted the light stayed on and the car started revving on its own not hunting but revving, switched off started again the revving stopped but the light stayed on. Someone might have been the factory told me to dissconnect the battery leave it for a while then touch the battery with the positive terminal a few times and to my amazement the light went out .Back on topic I think you might have issues if you remove the cats but in fairness my exhaust system wasn't connected up when i started the engine. Stupid question have you got a sports exhaust fitted some people think if you have a quad exhaust its a sports exhaust this is not the case on an Aero.

I have a switchable silencer on my Plus 8, but have kept the cats. Sounds epic under hard acceleration!

I thought there were a couple of options ?

Sidepipes or normal
Sports cats or normal.

You could have the sports cats with either exhaust design?

I was not aware there were secondary cats but the Coupe has the sidepipes and there would be no room to fit secondary's ?

Thanks guys

Great advice here.

One cat each side might just work enough but my exhaust man is suggesting if he fits the lambda at a 45deg angle or moves it further out of the exhaust air stream then it will read a weaker mixture.

Not too worried about a light although a pain. Just didn’t want it to try and alter mixtures to compensate but from what I’m hearing it only throws a light.

I have. Librands system with the under sill silencers effectively piped through so just running the cats and rear in pipe resonators to silence it. It’s still fall to quiet.

I might take a cat off and get a pipe made.

Will report back.

I did the same on my V8 Vantage, couldn't be happier with the results (but there I have an exhaust with the valve)
I was not aware that the Aero had a secondary one (but noisy enough wiht the side pipes).
Does it have some sensor on the sec kat? EarlierVantage had it.

Watching this with interest, seems mad having 4 standard cats on these, I would love to delete 2 and replace the remaining with sports versions..

Does sombody have a pic of where the second one is?

This was my full rear exahust.
https://www.facebook.com/photo/?fbid=266121430240087&set=a.266120833573480

And no space for the secondary one with the side exhausts
https://www.facebook.com/photo/?fbid=266121566906740&set=a.266120833573480

Just before that there is the main kat, this
https://www.facebook.com/photo/?fbid=499111936941034&set=a.499111573607737