cut out the cats?
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
The cats on the LT1 are not very restrictive.
On a stock engine, unless they are malfunctioning you probably won't notice much (if any) HP gain.
It might sound a little different though.
On a stock engine, unless they are malfunctioning you probably won't notice much (if any) HP gain.
It might sound a little different though.
Racer
Joined: Jun 2010
Posts: 402
Likes: 1
From: Tabernacle NJ
A few reasons not to:
Won't increase power or torque.
If stock (original), you're likely to break bolts trying to take them off. Hassle.
Violation of Federal Law. Regardless of local emission testing laws.
Hollowed out cats tend to sound kinda...crappy.
My vote is no. Unless they're failing and you just need to get by until you can replace them. No need to pointlessly pollute.
Won't increase power or torque.
If stock (original), you're likely to break bolts trying to take them off. Hassle.
Violation of Federal Law. Regardless of local emission testing laws.
Hollowed out cats tend to sound kinda...crappy.
My vote is no. Unless they're failing and you just need to get by until you can replace them. No need to pointlessly pollute.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
In my neighboring state of MO, they only look for functioning CATs. They don't really care as much about EGR/AIR. That, plus some other things I've read, lead me to believe CATs are the best emissions contribution in the past 30yrs. Aftermarket, and some stock converters, don't really restrict the flow of your system THAT much. IOW, CATs are worth keeping on street cars. (I don't feel that strongly about AIR/EGR though.)
If you removed yours, you'll be more likely to think your car is faster because it would get louder. CATs do muffle. If you need new CATs, consider a good, aftermarket highflow Magnaflow, Dynomax, etc....
If you want more power, remove your mufflers and see how you like that. That will also get louder/more agressive. The HP gain would probably be about the same.
If you removed yours, you'll be more likely to think your car is faster because it would get louder. CATs do muffle. If you need new CATs, consider a good, aftermarket highflow Magnaflow, Dynomax, etc....
If you want more power, remove your mufflers and see how you like that. That will also get louder/more agressive. The HP gain would probably be about the same.
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
No emissions testing in Most of Missouri. Only in St. Louis and perhaps Kansas City.
The rest of the state just does a general safety inspection.
But as thedudeman321 mentioned it is against federal law to remove them, regardless of any testing or not.
But unless you live in an area where they do actual testing, I doubt anything would ever come of it.
But as I stated in my first post, by the time the LT1/LT4 was introduced cat technology had made vast improvements over the earlier very restrictive cats of earlier years.
Look at the newer high performance cars now, getting 425+ HP (and even over 600 HP with the new ZR-1). Those cars are all using cats.
The rest of the state just does a general safety inspection.
But as thedudeman321 mentioned it is against federal law to remove them, regardless of any testing or not.
But unless you live in an area where they do actual testing, I doubt anything would ever come of it.
But as I stated in my first post, by the time the LT1/LT4 was introduced cat technology had made vast improvements over the earlier very restrictive cats of earlier years.
Look at the newer high performance cars now, getting 425+ HP (and even over 600 HP with the new ZR-1). Those cars are all using cats.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
And my point was HOW/WHAT they look for when they do test. IOW, if it's strict testing, you need everything. No or safety testing doesn't matter. In some areas, they only care if CATs are left in place. I think that's because of the reason(s) I posted above.
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