Is there a point to buy a High-Flow CAT?

I have a Flowmaster 40 series on my 2001 Tacoma. It sounds good, it isnt that loud, but it sounds really good. No rasp, pretty deep, and sounds like a truck. Not a fart can.

Will I gain any performance or volume with a high-flow CAT?

Any personal stories about them?

 

no personal experience, but i'd guess you wouldn't see any performance change, but would probably get some volume

 

I have a high flow cat on my 91 toy. Never noticed a difference

 

Even then, they still flow pretty well.

Unless you start pushing alot of volume, or start running a rich AFR, no need to do anything with the rear cats. Front cats should be replaced with headers if possible.

 

off topic question in relation to this thread (i apologize), but isn't there a sensor screwed in to the header/first cat assembly (i can't remember if it's before or part of the y-pipe)? when you get new headers, do they have a tapped hole for the sensor?

 

I'm thinking of running a couple of high flow cats in my dual exhaust, to cut down on the exhaust smell.

 

Would be a good idea. Just need to keep an eye on ur afr. Too rich and u risk melting the cats.

 

No. The long tube and shorties both come with a bung welded in already.

 

Ok, I've not heard it called a high flow cat, I have heard free flow cat, which in terms may be the same thing. I was at a muffler shop and the man was looking at my cat and he told me mine looked old and could be clogged, its all rusty. Well he suggested a free flow cat, with has the outside shell of a cat, but just a straight pipe running through it. So in NC it will still pass inspection. He told me that there wouldn't be a hp gain, if there was it wouldn't be noticable. Also he told me that he runs one on everything he has because he says it gives much better air flow causing him to get better mpg. On the downside this may not be true he may have just been trying to sell a product to make money. But IMHO, in theory you would think just a straight pipe would cause louder exhaust, everytime air goes through a cat or a bend in the pipe it deafens it causing it to be quieter. SO in theory you automatically think this would work to cause your muffler to be louder, also better flow of air imo would cause better mpg. I too have a 40 series on my V6, and I too have considered putting one of these cats on.

 

I was looking at these, claim to flow better than some mufflers?
http://www.randomtechnology.com/

 

^^ agreed, mines pretty cruddy looking, thats why I was considering it.

 

Lots of good posts in this thread already.

The gain for the vast majority would be minimal if any. The only way to really know is to dyno run before and after. The increase would likely be small in the peak VE are of the engine. (Volumetric efficiency) Not likely to be felt with a "butt dyno".

Like XrunnIT says, sometimes a vehicle is pushed for power and boosted applications want to let parts out if they get lean. During had pulls, you will see tuner jockeys take AFR down into the 12:1 range from the normal 14.65:1 range for safety of the engine. You can see this done with cats on the vehicle as long as cruise AFR is close.

What he is talking about is a "test pipe" in a disguised shell. These have been illegal for street use for years. I know many people do this, but thought is was worth mentioning for those that would like to know.

With the new rules for cats on vehicles, the old way of putting a cat on based on size alone is getting more and more restricted. If a test pipe is installed there will be the need for a sensor simulator or other device to keep the MIL/CEL off. Those that sell them put strong notes on about them being "for off road use only" for a reason. The fines, if you happen to be the target of an enforcement action are not small.

 

Do you think that it would be worth it to put one of these on??? I mean I know that you don't really gain anything, but if I was to put one on would it hurt my truck in any way???

 

I'm reviving this thread instead of creating my own. I basically have the same questions that don't really appear to be answered fully hear (Though great insight)

2003 5vz-fe. 105k miles. Gibson 55112S muffler. Deckplate mod.

I will be installing a new front O2 and a URD sim as my CEL has been on throwing p0420 and p0135 (from memory, might not be 135... but something about no voltage to rear o2-yes i know i may need to replace this O2 as well but thought i'd see if the sim works and i'd get it anyway so...)

I'm about 100% sure my cats are shot/plugged. Trucks been getting 16mpgs with a 50/50 mix of city highway on my 15 mile commute lately. Feel like it's running 'wet' or bogged.

I'm looking at replacing the cats and there are a couple configurations out there that i'm looking at. I live in MN so no inspections, but have no interest in deleting both cats.

The way i see it, my options are:

This in the front:
http://www.autopartswarehouse.com/s...intcmpid=Product+Listings+Best+Seller#reviews

or this:
http://www.autopartswarehouse.com/s...c=Front&intcmpid=Product+Listings+Best+Seller

Has anyone had exp. with either company?


Then either replace the 2nd cat with a 'test pipe' or slap in another 'high-flow' cat for ~$100 - I think i'd prefer to keep two cats even if they're high flow...

http://www.autopartswarehouse.com/s...vetrain&intcmpid=Product+Listings+Best+Seller

or

http://www.autopartswarehouse.com/s...71.html?intcmpid=Product+Listings+Best+Seller


Any help is appreciated.

 

Don't mean to thread jack, but didn't feel the need to open a new one since this is already up and going.
I have an 03 double cab on 35's and a 6" lift. installed a TRD supercharger and just had it tuned with an ECU MAP 3 running a URD 7th injector. truck runs like crap as far as power goes feels like im towing a boat everywhere I go. after reading a lot of posts online im starting to think that maybe my cats are plugged which may be causing my power issue. was Wondering what hi flow cats people recommend for this setup or if the 35" tires are whats just causing my power issue?

 

Who tuned it? What are your AFR's? Did you have a chance to look at your timing map? Did it run the same prior to the Map-Ecu3?

 

I had the URD before and it ran lean all the time so I gave up with it. AFR on map ecu 3 are 14.7 up to 3 Ibs of boost then runs in the mid 13-12 AFR till 5 Ibs then goes into the 11-10 AFR close to 7-8 Ibs of boost. And 10 AFR under WOT.

 

Had a local shop called dynosaur performance tune it. Also know as power house performance.