To cat or not to cat?!?

[movinalong]

After my shorties come in I plan to build a Y-pipe with mandrel bends. My question is if you didn't have to(which I don't) would you leave the cat or get rid of them. I'm assuming the rear O2 sensors can be turned off with a tune.


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[Arctic-Rodz]

yea you can turn off the o2 sensors with a tune.

as far as taking them off, unless its for the purpose of performance upgrades you should leave them on or get high-flow ones.

 

[movinalong]

It would be for performance reasons I suppose. Thanks for assuring me that they can be turned off I wasn't completely sure



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[TheSatinPumpkin]

Emissions? If you have no issues with fitment space w/ the shorties then i will just leave them on. As mention the rear sensors can be turned off via CMR.

 

[Caldwell]

I would say leave them on. I would say take them off if you were going to be running boost, and there are no emissions issues where you live. there wont be a huge performance gain by removing them. maybe 2-5 WHP I would guess ?

 

[movinalong]

Ok that simplifies what I need to build a y-pipe I'll just leave them and start after. Thanks for all the help.


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[LETHAL GTS]

I would go with a high flow cat.
if you are driving on the street and not strictly racing that is.
Without cats you can get that raw fuel smell from time to time which can be hard on the eyes. At least I do once I removed the cats on my GTS.

 

[movinalong]

The truck drags from time to time but that's usually just when your typical stang owner thinks he owns the fastest car in the world lol. If there's not that much flow difference between stock and high flow I'll just leave them and put that money tears a VVT cam.


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[charonblk07]

As someone that has removed the cats, unless you're planning to run bigger hp OR you just want a ridiculously loud exhaust, then leave them in place. The stock cats will flow up to 450hp, beyond that you may be spitting out chunks onto the ground. Highflows don't last much beyond that unless you start paying the big $$ (~$900ea) to get the extreme flow cats that will typically support up to 800hp and are used on the top end builds where the owner is dead set on keeping the cats for legal purposes.

 

[movinalong]

Are you taking 450hp on the ground or the flywheel? Because ones no that hard to get I can cut them off we don't have emissions checks in Mississippi yet, so no worries there. It's goin to be JBA shorties and a corsa cat back it's a little quiet now so maybe the extra rumble will be nice.


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[charonblk07]

I always talk hp to the wheels, there's more variables involved but it's easier to measure.

 

[ATXHEMI]

I have hi-flows for the sole purpose to kill the smell. The smell while idling gets pretty bad. Especially with the windows down.