2.5" to 2.5'' CATALYTIC CONVERTER QUESTION

[The Zork]

Hi brains trust. Hope you can help.

I recently installed a Kraken on the SE. The dump pipe did not come with a catalytic converter, and it was dyno tuned without one.
To make it street legal, I am looking at welding in a cat. My system is a 2.5'' stainless steel SMB.

Question: What do I need to know about fitting a new cat inline? What size and what internals to prevent an engine light coming on and pass a RWC.
Or does anyone have one to sell?

[greenMachine]

I have one, but it may be only 2.25". It came off the GM, and I can assure you there was absolutely NO flow restriction ... . I'll check the size and PM you the result.

I assume you have an aftermarket ECU? How would it know anything about the cat? My first port of call would be the tuner who did the tune, he'd know about CELs and how to avoid them.

[Roadrunner]

SE doesn't have a post Cat sensor like same age NB's do so you're all sweet. Just get a 2.5" cat welded in and off you go.
I recently had MX5Mania change a 6year old collapsed 2.5inch Magnaflow cat with I think an X-Force one. No issues.

[Roadrunner]

Wait sorry you said it doesn't have a Cat in the Dump Pipe The US SE/MSM has 2 cats, one in the dump pipe and one further in the exhuast pipe just passed the gearbox like all NBs have. Aus SEs only have one in the exhaust itself. The oxygen sensor is after the dump pipe but before the inline cat.
Are you wanting to run 2 cats or did I misunderstand?
But that aside, if you are aftermarket ECU I doubt it's reporting pre and post cat sensor readings if you even have them.

[The Zork]

I assume you have an aftermarket ECU? How would it know anything about the cat? My first port of call would be the tuner who did the tune, he'd know about CELs and how to avoid them.

Thanks GM. Let me know if it is 2.5'' and SS. I do want the guts in it though.

[The Zork]

SE doesn't have a post Cat sensor like same age NB's do so you're all sweet. Just get a 2.5" cat welded in and off you go.
I recently had MX5Mania change a 6year old collapsed 2.5inch Magnaflow cat with I think an X-Force one. No issues.

I see some CC quoting 200 or 100 cell. What would be best. The car is tuned for street and track at 235RWHP.

[Roadrunner]

The higher the better it is at pulling the nasty stuff out. I'd be looking at 400cel minimum.
$135.00 from Mania for 2.5inch

[The Zork]

The higher the better it is at pulling the nasty stuff out. I'd be looking at 400cel minimum.
$135.00 from Mania for 2.5inch

The higher the number, the greater the restriction?

[greenMachine]

Thanks GM. Let me know if it is 2.5'' and SS. I do want the guts in it though.

Well, I was going to let you have it for free, but if you are going to be fussy ....

[The Zork]

Damn GM,
When I didn't hear from you, last night I bought a new one.
Appreciate the offer though