Does Free Flow Cats Change Exhaust Sound

[99 Sidewinder]

Does free flowing cats change the exhaust tone?
Are they louder that the stock cats?
How much performace gain are they worth over the stock cats?
Thanks for any info...

 

[PhilC]

The Hi flow cats do change the sound (louder) a little. As far as the gain, I did not dyno before and after so can't tell you precisely, but by sotp feel there is a gain. I believe that it is definately a good thing to do especially if you have headers and performance cat backs as the stock cat will then be a bottle neck. I went to them while seeking heat reduction and it seemed to have worked for me.


Good luck

Phil

 

[JonB]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by 99 Sidewinder:
Does free flowing cats change the exhaust tone?
Are they louder that the stock cats?How much performace gain are they worth over the stock cats?Thanks for any info...
<HR></BLOCKQUOTE>

Hi flow cats work as an integral part of a complete SYSTEM.

Generally, the higher-flowing cats deepen the sound, and MAY increase the volume, but only IF the rearward restrictions are minimized. Deepens and gets even louder with free-flowing performance headers.

As far as HP gains, AGAIN, the answer is based on all the other components of the SYTEM...and THE YEAR MATTERS!

If you simply add hi-flow cats to a stock Gen 1 car, and do NOTHING ELSE, you'll gain ~~10HP and waste $$. However, as an integral component of a performance exhaust SYSTEM, those same cats might free up 15-25HP for a header/cat-back system vs. STOCK cats. Gen 2 a bit less. 2000-2001 a bit less again.
A bonus: less sidesill heat. OE cat heat often discolors paint.

And NOT ALL CATS are created equal! The $1500 honeycomb metal substrate cats of the 'V-12 BMW Tuner Set' are now available for Vipers, still at a hefty $649/pair, DOUBLE the price of other hi-flows, but give +5~10HP over ceramic.

 

[99 R/T 10]

OK, I would like to chime in on this if I may. Since I own one of those Gen I cars. My plan is to replace the entire exhaust with Borla headers and no cats, running Borla Sportsman round mufflers with an exit to the back of the side sill. Just to be conservative(and please anybody correct me if I am wrong) I should see an increase in HP of 40-45 HP. I am going to dyno before and after. I was told that it is possible to LOSE HP if I have no cats. Although this may be true, I haven't ever heard of that, anybody?

Mike

 

[Motor City Mad Man]

How would I know if hi flow cats were installed in my car by a previous owner? My headers and Borla exhaust were installed by the previous owner and I am wondering if there is a way to tell if it still has the stock cats or not.

 

[Nadine UK GTS]

Pull a sill, take a pic, and post here...I could comment (exhausts are one of my fetishes!!)

 

[99 R/T 10]

Good question, I would guess youmay have to take off the side sill and get a look at them. There must be a part No. on them.

Mike