Hey guys,

I have the roush legal exhaust and im wishing it was a BIT louder...

I believe my 2004 has 4 cats on it at the moment.. could i switch 2 of them for high flows? would that make a significant noise difference? would that be legal to do? also, would only changing 2 of the 4 mess up the O2 sensors? Thanks!

 

Or could i take off 2 and leave 2? would that be legal? lol

 

What state are you in?

 

Cut out all four and replace with 2 hi-flows, then mount the 02 sensors after the cats. Problem solved...

 

Alright I'll look into that. How much will that cost do you think? Are high flows legal?

 

It depends what state you live in. Theres 49 state legal cats, and certain accepted in California.

A set of Magnaflow part #94106 cats to replace your rear cats would help alot, or maybe if you can find a shop to do so, just delete the rear cats in general, I did and am much happier.

 

$67 per cat on performancepeddler.com, and you can actually get them cheaper on that site. Just type in your best offer when you mouse over the add to cart button. If you live in Gayifornia, than you won't legally be allowed to modify your cats, period. If you live in the other 49, then almost any shop will swap out your cats for $100-$150. You can also get some cash for you old cats if you know where to take them.

 

Alright sweet. Thanks for the help man. I'll definatelu look into that! Just need a LITTLE more sound. Roush legal is QUIET.

 

Is that $100-$150 just to swap them out? Not including the new cats? So you're looking at a grand total of somewhere between $230-$300 for parts and install? I asked the shop that has done all my exhaust stuff and they said $300 for 2 magnaflow high-flow cats installed. Is that right?

Also, I have a 2002 F150 Supercrew FX4 with a 5.4. Which Magnaflow Cats are right for my application? Are there multiples that will work or is it just one that fits? Thanks for the help.

 

Sounds like a fair and average deal. Lucky they will replace 4 with two. As long as the cats are 94000 series cats that are 2.5" with 6000GVWR ratings you'll be fine. 94106 is the most popular to go with for its near cat-less sound.

 

Thanks Darren! Thats the right thing to do right, remove all 4 and replace with 2 high-flows? Thanks for the input.

 

Darren I may consider Maggie Hi-flows down the road. I have the 14" si/do out now, what set would I go with to sound like your set-up or just a hair quieter?

 

I would suggest to you the 94306 cats. They are the base version of the 94000 series cats ( t-304 stainless, 12" long body ). Its a tad more tamed than the 9" 94106 version. A few people on here have two 94306s with the 14" body SI/DO.

Sundevil did
http://www.youtube.com/watch?v=QfWmmwJnegA

And Andrew did
http://www.youtube.com/watch?v=EwDOFlPKce4

You have two options actually, replace all four with 94306s, or replace the rears only with 94106s. Our pre-cats in 04 & 05 models dont kill the exhaust flow and are the only cats monitored for O2 readings so it doesn't hurt to leave them alone, though 4 cats is a little overkill on the flow but since its a hi-flow cat replacing an OEM one there shouldn't really be a problem.

 

Thanks man. It would be some time before I could, but I would probably only replace the rears with the 94306's.

 

Why replace the rears? Whats wrong with leaving them off?