colbymh

Anyone using them, have them, or know of good ones to purchase?

Also, with them being less restrictive, will there be hp gains? louder/throatier??

Thanks for any input.

bob

Hi-flow cats, probably wont do much in terms of HP if the current system is capable of supporting 300+ with no restriction, becaue of their hi-flow nature, the cats will probably allow more niose to pass (my SLP cats were noticably louder when you hit the gas, otherwise they werent loud at cruise or idle).

Hi-flow cats at the stock stage of the game are like mufflers, they really dont add much in terms of power, but are really more about getting the sound you like and being emissions compliant.

turbo05gt

What ever you do stay away from dynatech cats!!

colbymh

Are they even worth buying then? I want some added sound, but I plan on putting borla stingers on anyway. If there isnt any hp gains from them, then I will probably scratch them off my list.

metroplex

I have high flow cats. Ford bolted them onto my GT at the factory.

SONICBOOST

They will open up the exhaust. I am looking for some highflow cats to go with my prochamber to make it a little louder

smileyjoe

I was just wondering if anyone has tried to have the cat's taken off their factory exhaust ? Wouldn't that be just like having an off road h-pipe ? I think the factory exhaust is 2 1/2 inch.

SC67Stang

I have High flows on the Magnaflow X-pipe I added.
Don't think the cats gave me any ponies but it did give me a louder sound at WOT. Did gain 5 ponies but more than likely from the X.
Sounds not much different at idle from before.

Pwny

How bad are dynatech cats? I saw a thread about one failing but how many people are having problems?

gloryboy

I believe it was Don W that had a dynatec cat fail and plug the exhaust pipe causing his engine to blow ......I had 2 different jba cats fail on me about 2 months apart under normal driving. Stay away from cats with a ceramic substrate (too delicate)......there are race cats that have a spun steel substrate that is much sturdier. I have been running a set for about 8 months with no probs.........got mine from a local muffler shop about 180 each, i'm sure you could do better on the price though.............as for gains, i have heard they are minimal in going to off road set up, so i doubt high flow cats get you much at all........

Pwny

How do you know when a cat fails? No exhaust coming out?

gloryboy

When mine went, it sounded like a couple of large bolts bouncing around in a metal can under the car. The ceramic substrate had fractured and pieces of it were rattling around inside the cat every time i stepped on the gas or hit a bump...........luckily the pieces never completely obstructed the exhaust flow.

TASSY5

Here is a good question for you Guroos.
I am putting a Whipple HO. SC on my car in the next week.
I currently have a Spydershaft 1 pc drive shaft and STOCK H PIPE with PYPES/Cervini's mid mufflers with side exits.
I had a Pypes ORH pipe but the side exit made it EXTREEMLY Too lous and Glass pack sounding so I took it off and put the Stock H Catted pipe back on. That did give me the sound I want for cruising but wish it were louder at WOT. (I guess i have to give alittle to get a little).
With the stock Manifolds and Catted H pipe will I be hurting the car as for performance not going with a Hi Flo Cat system or LT header system???

d_gusler

IMO the factory cats are already top notch. Its a waste of money installing hi-flow cats. I heard a couple sets installed on S197s, and they all sound like the factory units IMO.

TASSY5

what about LT's over the Stockers with FI ?

Pwny

Geeze. Glad it didn't end bad for you.

zaghloul

I think thats true. I can't think of any other difference.

gloryboy

With forced induction, LT's should be good for about 20 or so rwhp.......

Kluski

I installed a Bassani X-Pipe and kept the stock mufflers. At first I used the straight legs without cats. But the smell got to me after a while and seeped into the house from the garage. I put the highflow cats in. There is still a definete louder sound with the high flows, bassani x-pipe and stock mufflers.

Here is a clip with some different sound clips I made when changing my exhaust:

http://c5photog.ipower.com/MyCar/Bas...SoundMovie.wmv

RFLgtcs

so basically if i were to get LT headers and a hi flo catted mid pipe, the off road setup wouldn't be much of a different when it comes to airflow, hp gains, and loudness?

i was thinking of the american racing headers and hi flo cattted midpipe, does anyone know what those cats are made out of and if those are safe?