I have an '89 F150 5.0 that has the stock y pipe with both sides going into the cat. In the area that I live there isn't any requirement for emission inspection, so I just want to do away with the catalytic converter. I've shopped around and a y-pipe is hard to find without the cat as part of the kit, which raises the cost. I was thinking about taking a plasma cutter and cutting a large window on the side of the cat and gutting it, then weld it back together. Will this work?

 

Why not just go to an exhaust shop and have them cut it out and weld in a y pipe

 

A cat does not hurt performance. Is it bad or plugged?

 

In NC we don't have emission "testing" on anything pre-OBD II, 1995 and older but the equipment still has to be installed/visible. My '88 Ranger had a stand-alone cat so I removed it, drove a piece of pipe through it, welded it in place on both ends and re-installed it.No trace of any alteration and straight through path.

 

Ugg...

Leave the damn cat alone. They don't cost much and they do improve the air quality and it's less work to just leave it alone vs cutting and welding it back together. These aren't the pellet cats of the 70's. Those things truly sucked.

If you want better performance and sound, grab a CatCo 9303 Y pipe. It's a great performer and will get you more HP with a cat over a stock Y pipe regardless if the cat is gutted or not. They're a touch over $200.

Run whatever cat back floats your boat after that. I'm too old to want to rattle every window I pass, so I'd do a nice magna flow or flowmaster 70 series setup, but you can do glass packs, two chamber, one chamber or even straight pipe it. I've got a harley for when I want to check the sensitivity of car alarms...

 

I wish it were that simple. This one is the style that has two separate pipes (one from each side) going into the front side, and a single tube comming out the rear. It wouldn't be a clear, strait through shot to just ram a broomstick through it. I'm pretty sure it's gunked up and restricted. I bought the thing dirt cheap at an auction because it needed a motor. That's been taken care of now, but the way the thing smoked before, I'm pretty sure that the cat needs to go now. My budget is extreemly limited right now. Would like to figure out a fix using what's there.

 

Do like the one fellow said and cut out the side of the cat with a plasma cutter then dig out the guts and weld the cut piece back over the hole and you are done. The rear cat on these trucks you can just cut off and replace with a 3 inch muffler and pipe if you want, or if you wanna be dirt cheap and just reuse the rear cat and the stock muffler with just a small adapter to put it back together again then just cut the pipe and broom stick the rear cat real good and clean her out then just re-attach and keep on driving.

 

My '94 4.9L is like that too and already had the rear cat torched off when I got it. I put a 30" x 3" in/out Jones glasspack and "Y", from Summit, on it and installed the 2.5" duals that came on my parts truck. It still has a cat so it will hopefully pass it's first inspection. And being a 4.9L tractor motor one does not utter "performance" in the same sentence! It actually sounds decent. I'm good with my truck!

 

why not just fab a y pipe, or have an exhaust shop build you one?


sounds like a great time for long tubes.


and theres nothing wrong with running hi-flow cats...theyre cheap, easy, power loss is marginal. they make good mufflers too....

 

I cannot stand the smell of today's gasoline burned through a vehicle with no cat. It gets all in your clothes and stuff and gives me a headache. A high flow cat cleans up the exhaust and like already stated is also a muffler. My Magnaflow cat actually has a resonator made in the exit.

Run the truck some on the highway and let the cat light off and get hot. It probably will clean itself up and be fine. They really don't plug up much, takes a really nasty exhaust with raw oil. They do go bad and the ceramic cracks up sometimes or they can melt inside if a vehicle runs with a dead miss for a while on the road.

I had a '94 LT1 camaro that ran high 12s on radials, fast for the time. I came off the headers with a Y into the stock cat. It was mounted with header flanges and bolts. I made a straight pipe the same dimensions of the cat and went to test and tune one Thursday night. I switched back and forth twice that evening, the results were pretty shocking to me. I thought the car would pick up a 10th with the test pipe. It didn't. There was no difference I could tell in performance. I have ran cats on everything I have built since. Even older vehicles that didn't come with them originally.

 

I agree that you should just replace the cat when you have the funds. It takes quite a bit to clog one, but it does happen. If you are able to drop the cat, do the cut and gut on the top if possible, not the side. You don't want the tamper to be seen though most shops aren't going to say anything even if you take the truck somewhere. I gutted one from a F250 for a roofing company one year due to the truck not being able to get to the shop for a few weeks, but was running horribly. Luckily, it was a bolted on cat and was just able to drop it, stand it up, smack the interior with a crowbar and hammer then dump the contents. Basically, made it a straight pipe until it came back from the work site.

But as said above, personally, I find it better to have one than not.

 

Very few shops will do this because of the legality involved. While emissions testing varies from state to state, removing the cat from a vehicle originally equipped with one is illegal in all 50 states. I knew a local shop that was actually shut down and fined heavily after they were caught. I wouldn't be afraid to do it on my own personal vehicle because the chances of being caught or proving who removed it are very slim, but very few shops are willing to risk the liability.

 

This day and time I wouldn't cut a cat, even though I did back in the late 80's. Had mine still had both cats on it then it would have been MUCH easier to do my budget/use whatcha' got duals. Actually I'd have taken it and had the exhaust work done but I hadn't had mine on the road yet so I didn't know if it was going to be a driver or a parts truck. Exhaust work is a PITA!!!