Ok guys, same song second verse. 2003 FX4 with the 4.6, would like to squeeze a few more ponies and a little more mpg if possible, am also looking for a little more sound, you know trying to squeeze all I can out of these wimpy engines (My dad has the new Tundra w/ the 5.7 ). At first I was going to cut off all my cats and put in a x pipe, I have 2 dynomax bullets already, then it was cut off the rear cats, or just keep all 4. Either way the x pipe is going in. Thing is with mine I have an O2 sensor right in the middle of the larger rear cat. So... what if i cut off the first smaller cat with the 45 degree angle. Know this will flow better just kinda stumped on the sound? And with all 4 stock cats will the x pipe help any? And I know its illegal blah blah and in Kansas they dont give a rats ***. So anyone who wants to chime in is welcome. Guess I just need to go buy a diesel lol. Thanks guys.

 

Alright, finally, someone who actually wants a performance exhaust!

The best performing exhaust you can build would be a true dual exhaust, obviously, with the following:
1 set of Magnaflow Hi-flow cats
a straight-through muffler (not Flowmaster, or a chambered muffler)
2.25 inch pipes
mandrel bent pipes
X-pipe
and have it exit where ever you want and the tips are completely up to you.

You can have an exhaust shop weld some O2 bungs right after the cats so you won't throw a CEL.

 

Quick thing here. I thought a 3" si/so is best while true duals are best for supercharged engines. Maybe I am mistaken.

 

A 3 inch SISO is best for towing, but a well thought out true dual is better across the mid to high end of the spectrum.

 

Gotcha

 

Right and as of now i have all that but what should i do with the cats? Cuz right now i dont want to buy hi flows

 

Your best bet for cats would be replace the rears with two 94106 Magnaflows and have the rear sensors mounted after them, leave the pre-cats in place because they are loud and hardly resonate any sound. And stick to 2.25" true duals and X piped.

 

on my silver 2003 4.6 I had my front cats gutted, X pipe and two Dmax bullets, check my sig for my videos.

it was the perfect set up

 

So Darren right now can I just cut the rears off and keep or add performance? All Im worried about is performance cuz my x pipe is going on next weekend?

Thanks for all your input guys, anymore help is appreciated

 

[QUOTE=warhammer44;3814429] (My dad has the new Tundra w/ the 5.7 ). QUOTE]

id still rather have my f150. i could careless about their 5.7. you got a nicel ookin truck there

 

You should gain a little more torque by deleting the rears because the rears add in too much restriction to the flow. It took Ford 10 years to finally stop making the stupid 4 cat system and start using only 2. I gained a small noticeable amount of torque on WOT.

 

Alright, sounds like thats whats gonna happen then, one more question Darren. Low end torque, please tell me yours was the same or a little better? lol, thanks again.

Thanks, F1504WD, I love it, and its not done yet.

 

My low end suffered after getting the true duals done, improved mildly after deleting the rears, but still isn't as good as it was when it was a stock single exhaust. I'm custom tuned now and the power is very nice in the low end, but I know it would be even better with a single exhaust, but not as good of a high end power.

 

no problem . yours has a nice stance with just an aal and t-bar crank

 

From what I am running I feel as if I have gained a substantial about of horsepower.... well atleast its enough for me to feel a difference in the performance of my truck.
Im running:
True duals
Maggie high flow cats
2.5" Mandrel bent pipe
X-pipe
no mufflers.

Tommorow Im going in to schedule to get my Pacesetter longtube headers and my bilstein shocks, steering stablizer and cross drilled and slotted rotors put on.
After the headers are put on if I like the sound Im not going to touch the exhaust but if its too loud or too raspy I will be putting dynomax bullets on there.