High Flow cats with stock mufflers or Dual exhuast

[supermario]

Hey guys, Im sorry to ask questions that Im sure have been answered. Especially this being my first post.
Anyhow, I want to have the performance gain in my 97 Expy 5.4 with 150k miles BUT I dont want a loud exhuast like most aftermarket mufflers offer.
Here are my questions.

1. Do they sell hi flow cats that will pass California emissions?

2. Does magnaflow or flowmaster make a muffler that will work well but be as quiet as a stock muffler?

3. Is it better to do the cat back single exhuast with aftermarket muffler in 2.5" or 3". My neighbors says the best combo is a catback single exhuast in
3" with a magnaflow?

4. Would dual exhuast be they way to go with aftermarket mufflers.

5. Will I get a performance gain if i just install 2 or 4 hi flow cats and use a stock muffler?

I basically want to get all the performance gains but keep the Expedition as quiet as possible, i dont mind a lil noise but definitely want to keep it as quiet. What type of combos have any of you guys used?

Thankyou very much!!

 

[Racenut]

I am not to sure what all Magnaflow offers, but I am running the Flowmaster Big Block 70 series and it is not very loud until you step on it (it is just as long as the factory muffler but more free flowing)! Otherwise it is just a nice mellow tone.

I was able to find these catalytic converters that are made by magnaflow and state they are CARB compliant (But I would call to double check). They are closer to stock Cats but should flow a little better, just not sure these are what you are wanting. High flow cats for california use are almost imposible to find and when / if you do they are $$$$$$$$$$$$$.

http://www.summitracing.com/parts/MPE-47176/

http://www.summitracing.com/parts/MPE-47256/

The biggest imporvement for me was getting rid of the factory Y and running 2 pipes into a DI/SO muffler it got rid of the bottle neck restriction and picked up some good power ( I picked up even more with the rear cat delete but being that you are in cali you can't get away with it ).

Check out you tube for video's on different mufflers and see what you like the best but on the expedition remember that the smaller the muffler the louder it will be and the more drone it will have inside the cab!

 

[tallsville]

here is some info

http://www.magnaflow.com/02catalytic_converters/02product/02california.asp

http://www.arb.ca.gov/msprog/aftermktcat/aftermktcat.htm

http://www.spintechmufflers.com/catalytic-converters/cat_124.html

even companys from cali state that their hi flows are offroad use only. but can always find someone who will pass the car no matter what.

dual exhuast is best for performance but not sure if it will be as quiet as stock. mine was loud and constantly set alarms off.

 

[WHOISMOOTOO]

. mine was loud and constantly set alarms off.

thats an awesome feeling isnt it?

 

[tallsville]

yes it is. i still set them off but not nearly as much as with my duals

 

[supermario]

Cool thankyou guys very much. I will probably just go with a cat back, single exhuast "3 piping with a magnaflow muffler. I hope that will give some improvement over stock. I would love to do more but it gets expensive and not really worth the $ to hp gain.
My friend called a muffler shop and he said $320 for the catback exhaust. Thats sounds like a good deal, so I probably will go with that.

 

[Racenut]

If at all posible when doing the cat back try to get rid of the factory Y and run a dual in / single out muffler. The factory Y is really restrictive and for the little extra money you will see a large increase in performance along with a small increase in fuel economy.

The factory Y is almost more of a T and the exhaust gases fight eachother lowering your performance and fuel economy.

I was able to get my flowmaster for $150 and did all of the welding myself so for an additional $20 worth of pipe and fittings I had that Y removed and it made a big difference.

Just my .02

 

[joethefordguy]

my 2004 SSV has duals back to the muffler (I suppose because it is a police package) so it already has two cats with a dual exhaust from each manifold to the converter on each side. I'm thinking of replacing the cats with high flow cats then continuing back with dual exhausts to 2 mufflers and on out. I gather finding room for it all could be a problem. any thing else I should be on the lookout for?