Just had some questions about removing the cats when i put the exhaust on. iwill leave the o2 sensors. Can you tell me if it will hurt are gain thanks

 

It will hurt your pocketbook when u get a 25,000 fine for each one removed...Leave em on or replace them with high flow ones...

 

you will gain a little sound... u will lose alot of bottom end. the ones on the truck flow pretty good. back in the old days taking them off would increase some serious flow now days their so advanced that it doesnt matter ur gain wont even be noticable more then likely. save your time and get true duals with a balance pipe and it will be fine.

 

Too many zeros, it's only $2500 each. Good deal....

 

if it were me, i would just either keep my cats on and run straight pipes off of that or buy highflow cats from magnaflow. your not going to gain too much buy taking them off. remember a noise complaint ticket is WAYYY less then pollution tickets and even if your state doesnt have checks ( mn doesnt either) they can easily write you a ticket if they decide they want to tag you for as much as they can! i kno of many guys that use their trucks just for mud trucks and they still keep their cats on and have no problems with flow, taking them off will actually more then likely due more harm then good without a built engine that requires it.

 

Its still not worth the fine for removing the cats. The cats in total account for less than 1psi of back pressure in the exhaust. A good cat back system and headers will be more beneficial than removing the cats. Plus it will still meet emissions standards and these trucks tend to run better with some back pressure as well.

 

It won't hurt your engine and it will give you a little more power not much because these cats only have about 2.5psi of backpressure. And no matter what every one says backpressure is never helpful. If you go true duels use a x-pipe, it will keep the same amount of power on the low end. Be sure to use oxygen simulators on the two downstream sensors.

 

I wouldn't take them off $$$$$$$$$$$$, it's better to put on a set of high flow cats. Your not going to notice a difference between hi-flow and no cats with the new exhaust on.

 

Yonk the pre-cats...no CEL hassle, no TERRIBLE loss of torque, (especially if you have a muffler of some sort) and sounds a LOT better. Not to mention increased throttle response and mid to top end umph. No point in paying for the Magnaflow high-flows until you get 100K on the stockers.

 

Your FAR better off removing the muffler. I wouldnt take the cats off.

The reduction in back pressure is minimal and the cats actually help clean the exhaust "better for the enviorment"

I aint a hippy, I just dont see any reason to increase the amount of pollution your truck makes if it isnt going to help your performance any?

Remember also that when you decrease your back pressure, you increase your HP at the cost of Torque.

Pay attention to racerf150man's posts. It sounds like he knows what hes talking about.


Theres already a fairly lengthy discussion about this in the V6 forum.
https://www.f150online.com/forums/sh...d.php?t=201322

 

Actually removing the pre-cats doesn't add to the pollution, they are just there to get the truck to pass emmisions tests on cold start-up since they warm up so much quicker. After a minute or so the primary cats do the same job cats have been doing for years now. Don't remove all together...either do away with the pre-cats or replace both with Magnaflows if you want to spend the money. You won't lose much on the bottom end unless you're also running straight pipes. Even then my 4.6L ext. cab 4x4 can turn the 60 lb. 33's on command with 3:55's.

 

I am running two new hi-flow Magnaflow cats. They look good and in combination with the SI/DO Magnaflow #12158 the system sound terrific. Deep and strong growl. All finishing in two 4" Magnaflow slash cut SS tips.

My truck is 111K miles old so it wasn't a problem removing cats.

 

I have removed the back 2 cats and left the front 2 on my truck. Put in a single Magnaflow and cut the tailpipe off at the very last hanger. I personally like the sound and it keeps it way behind you for noise. I couldn't tell much difference in power when I did it, but it did seem to pull a bit higher on the top end.

 

if a cat is working correctly, it wont cause any restriction, and your states are pretty harsh, in md all we have to worry about is emission testing, unless there is a sound ticket given, at which point either a state trooper, or a qualified maryland inspector has to go over it, and sign the citation.

 

I will be removing my cats very soon to replace them with one single set of magnaflow hi-flows. When Im at it I am going to have the front pipe hi-jet coated. The factory cats suck.