ok so i have an 04 f150(of course) with the whimpy 4.6 and i want a true dual but i was told if i delete the cats i would have a check engine lite and i wouldnt be able to get it to go off. is that true? i want my truck as loud as possible and as much hp gain possible too. i was thinkin bout goin with a 3" manifold back until i got headers. any suggestions or comments would help alot. thanks.....


p.s. ive heard of distance friends and other ppl have it true duals but never got the logistics about it.

 

I don't know the exact exhaust route on the 04. I have an 02 that I had the rear cats gutted and true duals with Super 44's dumped right before rear axle on the passenger side. No check engine light yet but that is the back set. Going to get the front set gutted tomorrow and see if the light comes on. (I chose to leave cats installed for inspection purposes.) Called Troyer Performance for the X3 programmer and told them what I did with the cats. They said the X3 can't clear the check engine light from the O2 sensors. Hope that helps some.

 

try get some mil eliminators i had them on my mustang when i removed my cats.i forgot where i got them from though.

 

If you delete all 4 cats, yes you will get a CEL.

If you delete the rear cats only you wont, the rear cats are not O2 monitored so they can be removed without setting the CEL.

VMPtunings tunes will disable the O2s, and offer a better tune if you ask me.

 

What about gutting the fronts and removing the rears? Will that still get a CEL? If so, does it really effect anything besides the CEL? I ask because I'm about to have just that done in about 8 hours from now. I'd hate to find the truck won't run right and have to purchase a set of magnaflow cats because of it.

 

Yes it will because gutting is the same thing as removing the cats. There wont be a catalyst inside to burn the gases. It wont kill your performance but in winter your engine valves will be at risk of bending since mufflers are either chambered or straight through with no filter to block the cold from coming up through the exhaust, start ups will be risky when really cold. But your truck will still run well.

 

Gutting of front cats complete. Rear cats removed and replaced with straight pipes. No CEL. It sounds great and noticably better response. Mechanic said front cats were clogged up pretty bad. Now I have to conquer the idle flucuation and weird noises after the MAC CAI install.

 

Really? No CEL? I would figure if the fronts dont contain their catalyst and theres no rears a CEL would light up. Well congrats thats awesome.

 

yes you will have a check engine light unless you run anti foulers or custom tunes to shut it off.And without them,you will lose some low end.A cross over pipe of some sort will help with that.And the cold air going up the pipe gave me a good laugh.Thanks,I needed that .

 

Well 40 miles now and still no CEL. Just sounds like it got even louder. Think I'll throw on a moto blue CAI if friend finds it or an Air Raid since Troyer offered me a package deal on one with an X3. Either way everyone around town that I talk to keeps saying it has to be the MAC CAI. We shall see.

 

Its not a joke. I dont give mis-lead information. No mufflers and no cats does risk the valves bending at cold start ups. If you think about it, exhaust reaches a high temperature from the front and stays cooler towards the rear. Those colder those valves are, and then the instant torque of the crank and heat of the combustion will risk bending valves. My buds 305 Chevy had this experience.

 

ya know i have heard about the bending valves too.i had heard that it happens on a vehicle with stock exhaust that has an exhaust leak before the muffler.

 

A chevy 305 is a completely different animal then a modular engine.The cats stil have straight holes through them so they are not stopping air.It is a complete myth.Run it that way on every vehicle for 10 years without a problem ever.If a valve bends,it is a coincidense.been like that on my wifes 05 for 2 years with planty of 0 degree weather.The valves will not get any colder with wind blowing on them then without.Wind chill is different then ambiant temperature.Its a myth.And yes you are giving mis-leading info.

 

That is completely different then him trying to say cold air blowing up the exhaust pipe bends valves.And its mainly a leaking exhaust manifold.

 

He's not joking, and he is correct.