stock cat or high flow

[93xplorersport]

ok since there are so many people thats adamint on haven the cats on our trucks would a high flow cat be worth the money or just buying a brand new stock cat be better? and something i dont know how to tell is if my truck is equipped with cali emissions

 

[lifted93xplorer]

High flow cats have a great deal more flow than stock so it's your call on whether or not you want to spend the money. When I worked in a shop that did alot of exhaust we always sold universal highflow versus direct fit to save the customers money. Look on your emissions sticker under the hood if it's still there and if it's california it'll say it on the sticker.

 

[Anime]

Most replacement cats are already high-flow. Even the stock cats flow pretty well with the 2.5" pipe that's on there.

The direct-fit replacement converters from Carsound/Magnaflow and Walker are pretty high flow units.

You can put a single 2.5" universal high-flow 3-way cat on there, it won't be much difference over just replacing with a aftermarket direct-fit unit in terms of flow, though.

 

[2000StreetRod]

Dual cats?

If you have the "Y" or "H" configuration with dual cats then I doubt that you need high flow unless you have forced induction (turbo or supercharger).

 

[93xplorersport]

what you mean by the "y" of "h" configuration? all i can tell you is that from the manifolds it goes to back to back cats and then to the stock muffler then out to the back behind the left rear tire

 

[2000StreetRod]

Y vs H

I seem to recall that you have the older "Y" configuration: the downpipes join together in a Y and the output of the Y connects to the input of a cat followed by another cat then muffler. The Y allows the two banks to equalize pressure.

I believe the later "Y" configuration has a cat after each downpipe and the outputs of the cats join together in a Y and the output of the Y connects to the input of a single inlet/single outlet muffler.

My SOHC has an "H" configuration: each downpipe connects to its own cat, the outputs of the cats connect to each other and a dual inlet/single outlet muffler.

Each of my cats only have to pass half of the exhaust. In your case both of your cats have to pass all of the exhaust. Your configuration may benefit from a high flow cat.

 

[94Gexplorer]

so if you put a high flow cat on after the y-pipe then remove the second one and just go to the muffler would that hurt or help? i dont understand that whole double cat thing

 

[2000StreetRod]

Clearance issues?

There was another thread regarding this recently. I posted a photo of one of the factory equivalent replacement systems with the cats in series. I suspect the reason that two cats were used is that there were clearance issues such as being able to remove the transmission pan or something else in that area if a single larger diameter cat was used. Take that into consideration before going to a single cat system.

 

[94Gexplorer]

so what if you take out both stock cats and put in a high flow just behind the tranny? would it be a bad idea to just weld the cat to the muffler
also i was thinking since its right next to trans it would heat it up more causing the tranny to go out sooner than if you have it further back

 

[2000StreetRod]

Magnaflow cats

Below is a photo of a Magnaflow OEM cat replacement. I don't remember for which year.

I'm not that familiar with your model but I've been told the one above differs from stock which doesn't have the pipe between the two cats. With no first hand information I can't advise you on the best approach. I suggest that you try and get more reliable information from the various cat manufacturers that have a replacement for your specific vehicle.

Cats are fairly expensive. If you weld a cat directly to the muffler you would have to replace the cat every time you replace the muffler.

You have to consider replacement of O2 sensors, transmission filter, and anything else in the vicinity. I believe there is at least one year (maybe 1994) of the first generation that had a single cat running parallel to the side of the transmission.

 

[Anime]

That looks almost like the converter for the 91-94's but not with that diagonal center pipe. That might be an ideal design, though, since it would possibly let you use a straight pipe from the converter to an offset muffler inlet, instead of a curved pipe.

Stock replacement from Magnaflow is the #23388:

The reason behind the 2-housing cat (first housing does the reduction, second does the oxidation) is usually just how the emissions system was designed with regards to heat, since how well an emissions system works depends on what temp the exhaust (and converters in particular) get up to in order to start and maintain the chemical conversion process.

Sure, you can take off the stock converter and pop on a single 3-way. It might not be as ideal emissions-wise, but theres also the chance it could be an improvement, depending on where the cat is located between the Y-pipe and muffler.