Really...... FAST CARS DO NOT HAVE CATS. 
ORY vs. Hi Flow Cats
ORY vs. Hi Flow Cats Thinking about these Dynatec Supramax headers with hi flo cats. Plans are for head/cam car. My other option would be ORY. Do you think the Supramax headers would noticeably choke me down compared to ORY?
Staging Lane
Joined: Nov 2005
Posts: 66
Likes: 0
the ory might produce more rasp depending on your driving style, for a head and cam car you will see a slight 5-10hp loss with 215 heads and a 228 or bigger cam, i am running cats as long as my car stays full bolt on, when I go to heads/cam/intake90/90 i plan on getting a n ORY, also keep in mind some states have a HUGE fine for no cats, weight the cost and benefits
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
All states carry a huge fine for no cats because cats are mandated under FEDERAL law. If you're caught without cats, even in states without emissions testing, you can pay in excess of $10,000 for not having them.
Run the cats. It doesn't hurt a thing to do so.
Run the cats. It doesn't hurt a thing to do so.
ddd I didn't ask for advice whether to get cats or no cats. The question relates to how much cats will choke a head/cam car down (as measured in HP or torque).
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A little old but when we flowed these cats back in the day, we were a bit shocked. Onfire did the testing, I just took the pictures. 
http://www.installuniversity.com/ins...n11.122001.htm
http://www.installuniversity.com/ins...n11.122001.htm
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Verdad Gallardo ddd A little old but when we flowed these cats back in the day, we were a bit shocked. Onfire did the testing, I just took the pictures.
http://www.installuniversity.com/ins...n11.122001.htm
http://www.installuniversity.com/ins...n11.122001.htm
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
I'm interested in this thread too. I never heard of FLP cats? What's it stand for? I have seen Carsounds for around $70 a piece. Anybody know how good the universal ones on eBay flow?
In a issue of Hot rod, they engine dynoed a LSX motor and put different mods to it, I beleive it was a 6.0L, They installed the headers and gained great with the cats and then took them off, it made a less then 1 hp and 1 tq difference. Meaning they flow very well.
Now this was a bolt motor at the time of the dyno and then they stepped up to heads and cam, but left the cats on.
Not saying you cant gain but in the early test, it was pretty aparent, leave the cats on.
Now this was a bolt motor at the time of the dyno and then they stepped up to heads and cam, but left the cats on.
Not saying you cant gain but in the early test, it was pretty aparent, leave the cats on.
FLP went out of business *I thought* but it looks like they are back???? They use to have a header and cat system for our cars among other things for LS1's. Finish Line Performance I thought is what it stood for.
In a issue of Hot rod, they engine dynoed a LSX motor and put different mods to it, I beleive it was a 6.0L, They installed the headers and gained great with the cats and then took them off, it made a less then 1 hp and 1 tq difference. Meaning they flow very well.
Now this was a bolt motor at the time of the dyno and then they stepped up to heads and cam, but left the cats on.
Not saying you cant gain but in the early test, it was pretty aparent, leave the cats on.
Now this was a bolt motor at the time of the dyno and then they stepped up to heads and cam, but left the cats on.
Not saying you cant gain but in the early test, it was pretty aparent, leave the cats on.
I don't understand the mentality that running no cats is super bad for the environment especially when modifications have been made to the car that alter its fuel economy for the worse. And what about racing in general? Oh yeah thats super great there right? 
Remember more hp= more fuel. Engines are air pumps. More fuel=more emissions. No way around that unless you run "green" fuels.
I say gut the !cats unless you don't like the smell, want to control rasp, or have to pass emissions. If you don't have the money for some high-flows just gut em.
I had a 87 z28 with a tpi 305 (high school budget). It ran ok at best. I got it from an old lady that had it since new so it was NEVER driven hard. After a complete tune up at 85k it got at best 12-16 mpg. I figure exhaust should help so I buy a slowmaster cat back and you know what? It sounded great but still ran like crap. On a hunch I pulled the y and gutted the cat. AMAZING. It was night and day. I got 20mpg+ and the car was extremely quick for a 5.0. Raced a buddies 99 lightning and passed him at 65 and put a car on him by 100. Maxed out the speedo once (145 I think my memory is fuzzy). Car was honestly the fastest stock 5.0 tpi I have ever seen. I wouldn't have believed it myself.
I would bet that my improvement on mileage far offset the usage of a cat.
Granted the cat could have been clogged or whatever but the point is they are a restriction. End of story.
BTW my 02 does still have cats in place and I don't plan on yanking them.
Remember more hp= more fuel. Engines are air pumps. More fuel=more emissions. No way around that unless you run "green" fuels. I say gut the !cats unless you don't like the smell, want to control rasp, or have to pass emissions. If you don't have the money for some high-flows just gut em.
I had a 87 z28 with a tpi 305 (high school budget). It ran ok at best. I got it from an old lady that had it since new so it was NEVER driven hard. After a complete tune up at 85k it got at best 12-16 mpg. I figure exhaust should help so I buy a slowmaster cat back and you know what? It sounded great but still ran like crap. On a hunch I pulled the y and gutted the cat. AMAZING. It was night and day. I got 20mpg+ and the car was extremely quick for a 5.0. Raced a buddies 99 lightning and passed him at 65 and put a car on him by 100. Maxed out the speedo once (145 I think my memory is fuzzy). Car was honestly the fastest stock 5.0 tpi I have ever seen. I wouldn't have believed it myself.
I would bet that my improvement on mileage far offset the usage of a cat.
Granted the cat could have been clogged or whatever but the point is they are a restriction. End of story.
BTW my 02 does still have cats in place and I don't plan on yanking them.
Last edited by Lickeyman; Oct 17, 2007 at 09:52 AM.
