I am going to install a 3" Gibson cat back exhaust on my 97 5.4, in the past I have hollowed out (with the help of a big drift punch) converters, this has helped with high end output on a Camaro SS, Mustang 5.0, and my buddies Cummins TD. My question is, would it payoff to do the same to the cat on my 5.4 (84,000 miles, it may be clogged) or just leave well enough alone?
Any experiences??

 

It sure is a LOT of work to hollow out a CAT. Why don't you just install acouple hiflow CATs instead?

 

 

Ok, I think I am kinda an expert on this very situation. Really long story short: Don't ditch the cats! Go with a high flow cat!

Had an Audi that I installed custom exhaust on. Cat back. Was loud, but not too bad. After about 2 years 1 cat went out (Audi could not tell me which it was). $2,500 plus labor PER CAT from Audi! Talked to Tech, and a clogged cat is very bad for alot of the components in the car. Went to a local muffler shop and (after alot of me having to make sure and explain that I was not a cop, gov't agent or the like) finally cut my cats out and welded a pipe to re-connect.

Well, now the car was loud as hell (I mean like race car loud). That was not too bad, but the exhaust smell in the car started to get to me after a while. Well, I was going to live with it. Finally after about 6 weeks, I heard an odd noise while sitting in a drive thru. After taking a look I found that where the exhaust pipe goes in to the muffler had been eaten out. Took it to a differnt muffler shop and talked to the guy. Had new system installed plus had the Hi flow Cats installed. SOUNDED GREAT, NO SMELL, and really did not notice a difference in performance.

Go with the hi flow cats. Do not drive with a clogged or bad cat. It will shorten the life of the O2 sensor in the pipe as well other damage (cannot remember for the life of me what all the tech said).

I am not a tree hugging hippie that wants to make sure the air is good for us all. I am a car guy that wants all the power he can get out of the car, but while not tearing it up at the same time. Go with the Hi flows.

My $.02

Boxter

 

Thanks Boxter, I will look for the Hi-flow cat instead, (I assume that there is only one) I do not want to burn out the muffler.
Can anyone recommend a website that I can find aftermarket cats?

 

I suggest that you first crawl under your Expy and take a look around. I am not sure about the '97 but my '99 5.4L has two CATs. I think yours does as well.

I would also recommend that you have your OEM 'Y' pipe replaced with a quality aftermaket section as the factory Y has rather poor flow.

 

My '98 has 2, nicely stashed high between the frame rails I might add.

 

>I am not a tree hugging hippie that wants to make sure the
>air is good for us all.

>Boxter

Hey Hey! That Hurt. LOL.