I have an 05 5.4 Screw and the right side cat is making the marble sound and it is annoying as hell. Was thinking about cutting out the cats and replacing them with straight pipes and tuning out the check engine light for testing. No visual here on OBDII vehicles.

I would also replace the muffler with a dynomax or something similar.

Opinions on replacing the cats with straight pipe? Good/bad for power/torque? I pull quite a bit with it so I don't want to lose any torque.

Thanks guys.

 

Hello & welcome!

As is commonly known, cats store heat and that aids in scavenging - promoting torque. Removing same is not only Fedrerally illegal, but will be a bit detimental to low-end. Replace with hi-flows, and choose a straight-through muffler - stock size ( 2.5") -again to preserve bottom-end. Unless you have a larger budget, then other possibilities will present themselves.

Please read this classic post (from who most consider the Top F150 tuner) in it's entirety as it has more detail w.r.t the above:

==> https://www.f150online.com/forums/763041-post10.html

I do hope this help you in some small way.

Cheers & regards;

MGD v2.1e

 

It runs the same... I done this, then tuned for it, and it runs just the same.

 

^ Just sounds a lot better!!!

 

 

Yup - 'tis true. Read dat linky, buckwheat, Sir!


MGD v3.0

 

Buckwheat sir! lol

 

It helps with velocity, not scavenging, but I think if a truck is properly tuned to not have cats, it will perform better than with hi-flows.

 

Cats will hurt velocity! Not really sure what heat will do, but I know my butt dyno didn't know the difference either way! lol

 

Sir AV & Senor Punisher!

Gentlemen....

Do you realize how boring it would become if we actually agreed on anything?

You guys are the best. Thank-you for not being wimps

Cheers!


MGD v3.0