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Discussion Starter · #1 ·
The first owner of my bike put on a cheap chamber delete which required sawing a few inches the header pipe and digging out the secondary catalyst. Everything else is stock.

I’m trying to gather some educated opinions about how to move forward with this bike. So far I’ve ordered a used chamber and a fuelx to restore some back pressure and help the bike deal with the pressure from the missing secondary cat.

my goal here is two fold, I just want a smooth running and long living bike
Let me know what you think!
 

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Oh wow! Funny I seen this post. I just installed a AR Titanium Exhaust (CAT Delete) system on a 2022 390 Duke with ATOM (Coober) Tuner (Took 4 months to get my AR system)

Sadly Received a check engine light.... From my research I think its just probably running rich. I don't have a OBD2 reader yet to see the code. I have done the 15 min ECU reset process a few times.

I WAS SUPER SUPRISED to see the CAT is actually a part of the header system (non removeable) I think you are calling it the "secondary catalyst"

So if I am right... the exhaust flows down the header into the CAT ... thru the fins... that is not removeable (unless you cut it out) and then flows into the large Chamber... this is what I would call the Resonator. (Just reduce the sounds and creates a different pitch before heading in to the actual muffler) I do not remember seeing any actual cat inside the large chamber

I wish I would have taken a picture of the CAT in the header.... very odd. The only way I could see removing the CAT would be to drill it out or take a hammer and chisel to it like you mentioned. Or cut the pipe off and manually adding a new pipe. AR system does not come with anything to replace this section and would require a the proper SAW to cut it.

Since the CAT is technically still there in the header ....I think what I am going to do is remove the ATOM for now at least and put back on the stock air box cover and just run the stock ECU map. I could be wrong but I do not see how the AR midpipe and muffler would create any issues with the stock CAT still in the header. Sadly paid $1000 for a Titanium midpipe to lose the weight of the Resonator and have a "pretty" hi slung exhaust muffler lol!

If I did it again I would just keep the resonator "Chamber" installed and just remove the exhaust pipe which takes less than 5 minutes. I actually prefer this sound and setup vs the AR pipe with no resonator

ugh! Lesson learned

Cheers!
 

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So there is a CAT in the Resonator Chamber?
No. There is a cat in the header at the front of the engine where there is a bulge in the pipe and a second one sticking out of the end of the header - which connects to the presilencer (what KTM calls the resonator).

It’s the reason the pipe was diverted under the engine to give room for the second cat required to meet emissions standards for the BS6.
 

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Oh wow! Good to know....So I wonder why AR says that the are selling me a De-Cat system, but does not change out the headers which carry the CATS. Their system only removes the large midpipe / Resonator chamber (Presilencer). Their AR Resonator connects to the end of the stock Header where the second CAT is.

Either way sounds like I can run the stock ECU and ditch the ATOM for now. (of course I need to put the stock airbox cover back on) When I eventually receive the ECU dongle / reader I can add the ATOM to see what code its throwing and causing the check engine light. I just didn't really notice any performance changes with the ATOM, maybe a slightly higher idle.

Really wish I had a local KTM tuner ..... the pains of owing a non Japanese bike lol!

Cheers!
 

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Discussion Starter · #10 ·
Now you mention it, it is odd. Maybe they expect you to run a decat pipe. I would recommend running the Atom unit and not just relying on the stock ECU.
UPDATE: I ordered a stock header with a much higher quality chamber delete from a junked 2021 and the fuelx just came today. So that should fit together much more nicely and I can pop the chamber back on for my first service and keep from voiding my warranty.
Also, what’s an Atom unit?
Bicycle part Tool Automotive exterior Bumper Auto part
 

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UPDATE: I ordered a stock header with a much higher quality chamber delete from a junked 2021 and the fuelx just came today. So that should fit together much more nicely and I can pop the chamber back on for my first service and keep from voiding my warranty.
Also, what’s an Atom unit? View attachment 55824
Don't know why the chamber delete pipe would have anything to do with your warranty? The chamber/resonator is a noise thing, not an emissions thing. If you're interested in selling the chamber delete pipe, I'm interested in buying it :)
 
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