I am looking at replacing the stock exhaust on my '88 F250 and was wondering what i should be ready to do if i decide to eliminate the cat? My stock cat has the o2 and a return of some sort on the top. If i do in fact eliminate it, what do i need to do about the return? do i need to re-route it somehow or can it be eliminated also? If i eliminate it, what affect will that have on the system and will it cause more issues down the line when trying to tune/keep it running good?

Any info and advise is greatly appreciated!

Steve

 

The "return" that you're talking about is actually just the opposite. It's an injection port to push fresh air into the exhaust to help with emissions standards. If you eliminate the cat, you can just let that hang and push air out, it won't hurt anything. Your O2 sensor should be before the cat though, so that wouldn't affect anything. If you have emissions checks in your area, you're going to fail without a cat though, and it's a federal offense to remove it, just so you know.

 

GNR22,

Thanks for the response. Luckily the truck is 25 years old and i no longer am required to have an emissions test. I am not sure if i am going to eliminate the cat all together or go with a high flow cat of some sort, but i am happy to hear that i have more options now without having to worry about the injection port.

 

I dont run a cat behind my motor. I dont plan on it getting checked in the small town I live in, and I dont tend to go far with the truck. But just beware that the cat acts as a really good muffler, and without it, other mufflers will be much louder.

 

I think i am going to play it safe and put on a high flow universal replacement. Thinking about going with a Flowmaster high flow cat and a flowmaster super 44 with 3" pipes.

 

You can rather safely go with or without a cat legally. I'd lobby for you to keep/reinstall a cat only cause it's a good thing to do and a little safer legally. Modern high performance cats don't hurt power or fuel economy. They just hurt your wallet to buy them in the first place but do a lot help the environment and we all like clean air.

What does hurt your fuel economy is your engine turning that stupid air pump that pumps fresh air into the old school cat. IMO a quality modern cat doesn't need the fresh air behind a fuel injected engine. So IMO best thing to do would be to install a modern high flow cat and remove all of the air pump equipment.

 

Go to a Scrap yard that scraps cars and see if they will sell you an aftermarket cat that they have taken off a vehicle, they only get paid $4. for one and are usually happy to sell it for $20, WAY cheaper than the $300+ people pay for those things.