69ford99

Hi, Im new here mostly post on FTE. I want to run true duals on my truck but don't know if the setup I want to go with is going to give me enough backpressure. I want to go true duals out the passenger side before the back tire like the lightning. I was going to run hi flow cats for the front cats and I have some cat deletes for the rear cats then in to a dual in dual out super 40 flowmaster. Should I not even worry about the front cats? I would like for it to be loud and sound good.

DHFF

I wouldnt try to delete the front Cats because it will run like BUTT. I assume you have an 04? I have seen the rears deleted and that usually works. Only thing I recommend is throwing in an X or H pipe in there after the front cats. If you run high flows up front and a pipe diameter that isn't HUGE you should still have decent backpressure. You may lose a little bottom end though because 04 and ups do like backpressure. Hope that helps.

NGM

If loud is what you are looking for then the Flowdisaster is the way to go. If you want lound and performance look into Magnaflow or Borla. Deleting the cats will not make the truck run bad. It will set a check engine light unless you have a CEL eliminator for the rear o2s or a tuner.

69ford99

I have an '04 FX4 Screw and the rear deletes have a spot for the O2 sensors, will it still make the cel come on? Also I was gonna go with 2.5" pipe.

DHFF

Negative, deleting the front cats on an 04 WITHOUT forced induction WILL make it run bad. The O2 sensor associated with the front cats will read bad, therefore causing the truck to throw more fuel than normal. Enough to throw black smoke (unburned fuel) from the tailpipe. That is personal experience, not opinion talking there. Unless you can make the computer ignore the O2 sensors, the truck will run like crap without any cats.

Also the most performance you will ever get from an exhaust system is contained in the cats. High flows do twice as much as JUST replacing the muffler. Muffler choice is 99% of the time a sound based choice and rightfully so.

DHFF

As long as the truck is properly tuned and not already having problems up front, (plugs, coils, etc.) it should be ok. I never had a problem with the one we ran. The 04 responded really well to rear deletes and high flow mags in front with an intake.