I've read so much about exhaust and CATS that my eyes are crossed. So I have a 2002 Screw with 5.4, True Magnaflow duals (2.25 in / 2.50 out), CAI with PHP custom tunes. At 200,000 miles my CATS are starting to go (P0430) and want to go from 4 down to 2 CATS. If I am understanding correctly I should remove all 4 and replace with 2 Magnaflow High Flow CATS where the rear CATS are now and replace the 02 sensors. This set up will not throw CEL. Do I have this correct?

Basically I'm trying to make sure I'm on track so as to get it right the first time.

Thanks

 

Since you're running true duals, it's hard to advise not knowing how your exhaust is set up. However I lean towards using Magnaflow's direct-fit converters.

If your reason for going from 4 to 2 cats is for cost, let us know. The rear 02 sensors I probably wouldn't worry about since they're only function is to verify the cats are functioning. But without having your truck in front of me, it's hard to say what you have going on. You can just cheat the P0430 code with $10 worth of parts from Radio Shack and a little soldering. Obviously that's not exactly legal, but it will suppress the code.

A scanner with live data would be most helpful. What you should be seeing is the front 02 sensors fluctuating rapidly, while the rear sensors hold relatively steady.

But if you have a welder and like to play with exhaust, go for it.

 

2.25 in / 2.50 out Maggie High Flows, true duals. At 200k I'm starting to see issues with CATS and 02 sensors so I want to improve flow if I have to make changes. Lower costs for Magnaflow High Flow CATS (vs OEM) and sound are nice but I'm more into performance. I don't want to cut corners but would like to reduce down from 4 to 2. Does that help?

 

To put it bluntly, there's little (if any) performance to be gained by removing the pre-cats. And you then run the risk of doing all that work only to have the P0430 code.

If you want to change the sound, consider tweaking your exhaust system. Maybe more aggressive mufflers switching to glasspacks.

I say this because Even Magnaflow doesn't offer a pre-cat bypass option for your truck. It would certainly be more economical for them if they did. Same applies for the engineers that designed the engine and truck. They exist for a reason.

If you're insistent on trying this out (which is cool), you could try a pair of higher-capacity converters (Magnaflow 51556) which may help compensate for the missing pre-cats.

I'll put the disclaimer here that I haven't done this and wouldn't be inclined to. Knowing that there's almost no performance to be gained over functioning converters. It's not like the old days when converters choked the life out of engines. Modern cats are designed for minimal performance impact for overall efficiency.

If you set about this journey, post some pics and if the P0430 doesn't return after a month, consider it a win. But have realistic expectations and be prepared for having to go back to direct-fit converters (which Magnaflow does an excellent job with).

 

ok i want to get in on this because i am already planning my exhaust set up for the 02 im looking at right now. It has a magnaflow exhaust on it(big one) already from the previous owner (besides the one that is selling it to me) so its been more than 10 years i would say, you almost cant hear it. So i want to change it, if i remember correctly when i had my 04 cobra. I did the same thing, i put the x pipe in the middle with 2 cats instead of 4 and just ran MIL eliminators ( i think that's the right name for them, its been a while) for the 2 back sensors. Does that same process not apply to the F-150???? because i would not want to mess with codes coming up after spending a pretty penny on the exhaust. Thanks and hope to hear back.

 

I believe the mil eliminator only work with the mustangs, I could be wrong but I remember trying the O2 sensor system is different, by that I mean the wires. If you go with Maggy high flow cats get the ones with the O2 buns in the cats, I believe. They shouldn't trip a cel.

Changing to a 2 cat system should make it louder, add a Borla xr-1 and you'll be golden.

 

I wanted to go with the magnaflow magnapacks. what do you think. Also, is there a company that sells and X pipe with the cats on there already?? sorry i know more on the stangs than on the F-150 and im guessing Maggy is the company on those cats you are telling me about. Thanks.

 

Magnapacks are good too, it's personal opinion on what you like in sound.
When I say Maggy I mean magnaflow. But I do not believe they make an x pipe with cats already on it kind the Stang's. I think they have direct replacement with a y-pipe tho.

 

BOOOOO hahaha ok well thanks for the info. that will come in handy. here is one more for you lets see if it you can shine some light into it. Im seeing the name Troyer performane alot on some of the thread. Is that a reliable company to buy from, for the 97 to 03 years they are saying that they have good chips/tuners to buy from them as well as the electric fans. Any info on that??? thanks again.

 

I have never personally dealt with them, but have heard really good things about them. Their lead time for custom tunes is measured in months not days tho haha. But for some reason I was thinking lately people haven't been able to get ahold of them.

This is what I was talking about.
https://www.f150online.com/forums/ch...ff-planet.html

 

thanks thelariat02 you have been super helpful

 

You're welcome! Myself (+many others) are always here to help.

 

Hey Guys, I haven't been on here on quite a while mainly doing a lot of repairs on my truck including a new A/C system, front end repairs, repairing oil leaks, etc. so with 215k miles it looks like I'm close to having her as good as new.

So an update on the situation with my CATS. Just completed the work recently. I now have a full true dual Magnaflow set up with two high flow cats and a new PHP custom tune to accommodate the change. Eliminating the four CAT set up has awakened my truck; more power, better flow and the sound is amazing. The key to moving from a 4 to 2 CAT system is a programmer using custom tunes specific to your trucks customization. Amazed at the difference this has made. Just thought you'd like an update even if it took almost a year to complete. Have a great day!!!

 

Good to hear back from ya! Glad you got everything working and keeping that truck in great shape!

 

I also have the p0403 code what would I Need to get from radio shack to bypass the code and the CEL light comming on? I want to get MagnaFlow high flow cats but money is a little tight right now as I just bought the truck.