HP difference: cats vs no cats
Thread Starter
Joined: Apr 2005
Posts: 2,169
Likes: 1
From: Dallas, TX / Boston, MA
HP difference: cats vs no cats (this question has probably been asked before, but i did a search and couldn't find it)
this summer i'm going to be getting some kooks LT's. the rest of my exhaust is the stock Firehawk SLP Catback (3" intermediate, power flo muffler). my major debate is cats/!cats.
does anyone have any hard statistics of the power difference between cats/!cats? if its a big difference, i'll go with an ORY and put some fake cats on it to pass the visual test, and if the difference is negligible, i'd get the catted Y and save myself the headaches of fabricating something that looks authentic.
i'm not overly concerned about sound level, since i'd think that the stock SLP muffler would keep the noise within the levels of reason.
this summer i'm going to be getting some kooks LT's. the rest of my exhaust is the stock Firehawk SLP Catback (3" intermediate, power flo muffler). my major debate is cats/!cats.
does anyone have any hard statistics of the power difference between cats/!cats? if its a big difference, i'll go with an ORY and put some fake cats on it to pass the visual test, and if the difference is negligible, i'd get the catted Y and save myself the headaches of fabricating something that looks authentic.
i'm not overly concerned about sound level, since i'd think that the stock SLP muffler would keep the noise within the levels of reason.
11 Second Club
Joined: Feb 2003
Posts: 5,524
Likes: 1
From: The South
Most people with stock cams and exhaust that exits out the back rarely smell fumes. I don't get them very often with a large cam and dumped duals.
It's pretty well agreed upon that you only lose a few horsepower to properly sized 'high flow' cats. Personally I would/do run an exhaust system or cat-back/muffler that sounds good without cats. That way it's not even a consideration.
It's pretty well agreed upon that you only lose a few horsepower to properly sized 'high flow' cats. Personally I would/do run an exhaust system or cat-back/muffler that sounds good without cats. That way it's not even a consideration.
TECH Fanatic
Joined: Nov 2003
Posts: 1,241
Likes: 0
From: MD
From the start you'll only be losing about 5 hp, 6 months down the road that may change to 8 to 10, a year who knows. The issue with cats is that they get clogged and like a slipping clutch may not get noticed due to the gradual change until you're missing 20 or more horsepower.
Originally Posted by Lithium
With an ORY your going to smell fumes a lot, I happen to like it but some people cant stand it. The power difference is around 5 to 7 hp between and ORY and a Catted Y.
Trending Topics
I made 439rwhp thru long tube headers and 3" cats with a true dual 3" all the way back running Magnaflow parts. On the sniffer my car at idle had high HC's because of the 233/239 cam... but at 2500rpm it was super clean.
Aside from cost there isn't much tradeoff IMO.
Aside from cost there isn't much tradeoff IMO.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
11 & 7 Second Clubs
Joined: Oct 2004
Posts: 1,299
Likes: 0
From: Motorhome, Freeways, Truckstops, Pits
My current setup from FM does not have cats and it is stinky and loud. I'm going to cut-in a set of high flow cats soon.
Originally Posted by slayer_taunu
(this question has probably been asked before, but i did a search and couldn't find it)
this summer i'm going to be getting some kooks LT's. the rest of my exhaust is the stock Firehawk SLP Catback (3" intermediate, power flo muffler). my major debate is cats/!cats.
does anyone have any hard statistics of the power difference between cats/!cats? if its a big difference, i'll go with an ORY and put some fake cats on it to pass the visual test, and if the difference is negligible, i'd get the catted Y and save myself the headaches of fabricating something that looks authentic.
i'm not overly concerned about sound level, since i'd think that the stock SLP muffler would keep the noise within the levels of reason.
this summer i'm going to be getting some kooks LT's. the rest of my exhaust is the stock Firehawk SLP Catback (3" intermediate, power flo muffler). my major debate is cats/!cats.
does anyone have any hard statistics of the power difference between cats/!cats? if its a big difference, i'll go with an ORY and put some fake cats on it to pass the visual test, and if the difference is negligible, i'd get the catted Y and save myself the headaches of fabricating something that looks authentic.
i'm not overly concerned about sound level, since i'd think that the stock SLP muffler would keep the noise within the levels of reason.
On The Tree
Joined: Jan 2004
Posts: 161
Likes: 0
From: Miami
I would go with ory (no cats) or + true duals (pipe all the way back from each header) if you don't mind a loud car & smelling fumes when you start up. I have the Jet-Hot headers + ORY and it sounds sweet. Cats are for dogs. 
Go with the cats if its a serious issue for you (inspection) / tickets / local laws or if you dont like the smell of fumes sometimes.
Go with the cats if its a serious issue for you (inspection) / tickets / local laws or if you dont like the smell of fumes sometimes.
