i've looked all through this site and have searched but i can't seem to find a write up on how to delete the rear cats on a 97-03 F150..
if anyone knows exactly how or can pointe me in the direction of a how to it'd be greatly appreciated..

thanks!

 

Would be the same way as a 04 - 05, except you might have the rear O2s mounted in the cat, or after it. You'll have to get them re-mounted then.

https://www.f150online.com/forums/ex...rear-cats.html

 

they're mounted slightly after.
thanks!

 

i don't understand how it won't throw a code if the O2 sensor is after the cats..

 

In your case its very possible, but some members who have done this on '97 - '03s reported no CEL, so the pre-cats must be filtering enough carbon and the rear O2s are probably covered in alot of carbon and reading in-perfect readings. If you do end up with a CEL you can add O2 sims to delete it, or if you are custom tuned them your rear O2 monitoring may already be disabled.

04 & 05 model trucks have the pre-cat, then rear O2, then the rear cat in place ( yeah they must have been smoking something in design right? But thats ok, it made a simple way to make exhaust louder ). I removed my rear cats without any CEL issues because of this, didn't even need to remove them when fabbing the new piping. The only downfall is I cannot pass emissions, and it smells a little cat-less on cold starts.

 

Did you have to take the replacement pipes to some kind of shop to get them flanged to slip over the other pipes?

 

No, I bought pre-flanged pipes and adapters from Napa, they were 18"s long, I needed to chop them down to 11.10" and I slip fit the adapters over, and we clamped them in. I had them welded shut not too long ago but still have a minor leak on my left pipe. I used aluminized pipe which I regret. When I look under the truck and look at them they aren't rust rotted but they aren't shiny pipe either.

When it looks like its going to hell I will try removing my exhaust, having my exhaust chopped up so its full bolt in with 2 point bolt flanges like this



That way my exhaust will be full bolt on, true dualed, I'd be able to change out to a few different muffler setups if I spend the time fabbing it together and buy more mufflers, and I could delete my pre-cats and so with 2 simple Magnaflow 94106 cats so it looks more legal than it does now lol.

 

ohh! full bolt on would be sweet.

the replacement pipe was my hang up with this. now maybe soon i'll be able to get this done!

 

i've got a 101,000 miles on the truck, so maybe the cats are still in good enough shape that they'll filter enough.
i've been seriously considering LT's with 2 high flow's but money's been a big issue. i figured i could cut out the rear 2 cats and sell them and go buy high flow's and have them welded up. but i'd need some tubing there in between getting it welded and everything.

 

I prefer welded.

 

If your going to get hi-flow cats there wont be a reason to run the pre-cats with them. Get the piping to delete the rears and if you plan on buying the Magnaflow cats, have the shop remove the fronts and replace them with the Magnaflow ones in the location of the old cats.

 

You should search with good keywords on google, you can easily find a solution for you.