High flow cat

[JimRummy]

Just wondering what you guy's feeling is on a high flow cat.
I have a Flow 40, and was just curious what, if any, benefits a high flow cat provides. Worth the $100 is the question.
Also I was talking to someone and they asked if the 93 4.0 had a resonator.
Wasn't sure.. If it does, and I remove it, does that help flow at all, or just add noise?
Many thanks!

 

[adsm08]

On modern vehicles (like, 1990 and newer, you know, EFI stuff), a high-flow cat does not really show any benefits over a stock unit unless you have done extensive work to the engine, intake, and exhaust system.

I know it sounds counter-intuitive but removing the cat actually hurts flow too. The system is setup to work a specific way, and the diameter of the system is part of the calibration. The cat is figured into that and helps the exhaust scavenge itself.


An Explorer might have a resonator, a Ranger probably doesn't. Ford was a fan of putting them on SUVs and not trucks. It's just a larger chamber in the system to help quiet it down, doesn't hurt or help really.

 

[JimRummy]

Okay, so like 90% of these things, not justifiable to replace unless it breaks. I have intake and exhaust, but was just curious if it was worth it.
I've seen some of the higher dollar packages come with a high flow cat.

 

[adsm08]

Have you ported, polished, stroked, bored, and boosted the engine?

If not, a high-flow cat is probably not the best place to spend your money right now.

Unless of course you need a cat right now.

 

[JohnnyO]

Agree, it's only worth the bother and expense if you need a new cat anyway. Magnaflow's unit doesn't cost any more than a stock replacement. Random Technology makes a highly-regarded hi-flow cat but they tend to be more pricey.