Last summer I modified the exhaust system on my car along with the cam swap and I put on some hooker LT's into a mufflex ORY and mufflex 4" exhaust. The car sounds great and everything it's just that waking up the neighborhood when I start the car or get home late is getting a bit old Also the car smells like gas if I let it idle for more than 30 sec. in one place although I suspect that maybe has more to do with the PCM (it's got a mail order tune) than with the fact that I don't have a cat on there. And there's the added benefit of not having to worry about the cops, although the cops around here don't seem to mind at all, I've come across quite a few of them, they never give me a hard time.

So anyway I called up random technology and it turns out they have a high-flow 4" cat that would run me 270$. So do you think it's worth it to put a cat on my car? Do you think it would hurt performance? I would guess my exhaust is pretty free-flowing, I don't think having the cat on there would hurt any, maybe I'll even gain some low-end torque (I don't seem to have as much compared to before).

Anything else I should consider? Would placement be an issue? I'm guessing I could just put in on anywhere after the y-pipe?

 

I have been thinking about two high flow cats in my Y pipe because of the smell issue and for the fact that if I start my car in my garage, the fumes cause a film all over the paint on my car that is difficult to get off. I have to use like a quick detailer to get it off. I found the cats listed on the site below that would be good for going into the Y pipe on each side and are small enough that they should fit fine. IF there is any power loss, which I don't really know if there would be much, it would be so minute that you would not be able to tell (maybe along the line of 5 HP). I think that it would be worth it. You could buy two of the cats below for one of the Random Tech's.

http://216.178.81.107/iwwida.pvx?;it...0%201?comp=ppe

 

Adding cats will go a long ways towards quieting yur exhaust down and getting rid of the gas/ exhaust smell. The best bet would be to use two cats right after the collectors on the y-pipe before the y. Adding cats might give a slight decrease in total upper end HP, but it will shift the HP/ torque curve down in the RPM band, thus you should feel more low-end torque. Hope this helps.

Schantin
2002 Camaro Z28 M6

 

I would NOT put only one cat in after the y-pipe. It will choke your exhaust to a degree, even if it's high flow. I had a high flow cat in my system, just one after the y-pipe. Stock, my car('97) came with dual cats, and the combined flow of the stock cats outflow even the best high flow single cat. I had a hard time justifying having a single high flow cat in there, when it didn't even flow as good as stock. Now I have a bullet muffler in there instead and am very happy with it. I doubt it would be enough to quiet down your exhaust. Maybe one in each side of the y-pipe would work. The bullet muffler is a little louder than the cat, but it's a deeper tone and it's straight through.

Now, if you go with one cat in each side of the y-pipe, that's a good idea. I'm not sure cats will get you THAT much quieter than you are now though.

Dan

 

I had an ORP pipe with no cats and yea the exhaust was louder but it stunk! I put the Cats back on and that's the best thing I ever done.

 

Wow Dan, that's the first time I've ever heard someone say that a stock dual-catylitic Y-pipe set-up off a '96-'02 car will outflow even the best "single cat" after the Y on the '93-'95's...I realize adding another cat in '96 was supposed to be primarily responsible for the "extra" 10 horsepower that year LT1 came with as opposed to the previous three years...But honestly, I've never seen anything on the dyno or at the track to show that a single cat car will run any worse than a dual cat car (assuming stock for stock). In fact, many single cat LT1's have dynoed higher and run better down the 1/4 as compared to the dual cat cars...So if there was really such a big difference in flow as you stated, I think we'd see it...Not to mention, single cat cars do just fine at high horsepower levels against dual cat ones from what I've personally seen too...Just going by "real world" experience, that's all...

And FYI, I did have a 12" Dynomax Bullet installed right after the Y w/ my Mac headers and I don't think the car is nearly loud enough! But I'm actually going to replace it with a good highflow cat as it is just a little too raspy in a small mid rpm range for me personally...I'm 100% confident there will be little flow difference between the bullet & highflow cat while the cat will get rid of the small rasp I have and kill that smell of gas at idle...I just don't see where the bullet will make that much of a difference in flow with my bolt-on set-up...

A good highflow cat will definitely quiet your car down as compared to an offroad pipe while cleaning up the tone considerably... But with your set-up, it will still be plenty LOUD overall...

Mike

 

http://www.installuniversity.com/ins...n11.122001.htm

If you follow that link, you will see that a pair of stock cats will outflow a single highflow cat.

Any restriction in the exhaust can hurt HP. There is enough restriction in our stock cats to make us lose HP. So going any more restrictive than that makes it worse. I'm not saying that you will lose 20 hp from having a high flow cat in your system. If I were to guess, I would guess 5 rwhp, but it depends on how much HP you are making. The more rwhp you have, the worse the cat is. That's the great thing about putting a high flow cat in each side of the y-pipe. It flows twice as well as putting a single high flow cat after the y-pipe.

I have a high flow carsound cat, and took it out for the bullet muffler. My MAC mids with the bullet muffler and Hooker catback don't have any rasp, and it's not too loud. Sounds great. I could tell that the exhaust got louder with the bullet muffler, but not that much louder. It also got a much deeper tone with the bullet.

Dan

 

I would have thought for sure that a single 4" hf cat would flow better on the exhaust than two 3" hf cats but I guess I was wrong. That's why I never really considered it. Also I wanted to run a single cat because I thought that if I had a section cut out of the exhaust pipe and had flanges welded to it and to the cat I would be able to jack up the car and interchange cat/straight through pipe whenever I wanted. I could probably do the same with the dual cats but it would be more of a pain.