I am looking into buying a replacement cat for Bank 1 on my 99 F150 4.6L. The descriptions list some cats as being for a 4250 lb GVWR and a 6000 lb GVWR.

The curb weight of my truck is about 5200 lbs, so I am assuming I need the 6000 lb cat. Is this correct? Does it make a difference?

Also, all the descriptions state that they do not come with ports for the oxygen sensors. Is it as simple as drilling a hole then tapping it out?

 

If one cats needs replacement, both of them need to be swapped. Don't pay money to have OEM cats swapped back in, save money and have hi-flow cats installed then have the O2's mounted behind the cats.

 

Have a couple Magnaflow #94306 cats mounted inplace. The 4250 gvwr cats are the pre-cats, which you should try to not have to replace, just delete them.

 

I want to do this in the cheapest way possible. Using Magnaflows are going to be expensive and probably will require professional installation.

I seem to remember the O2 sensors being mouted behind the stock cats instead of in them. I'll have to crawl under and check. If not, I suppose it would be pretty simple to drill and tap the pipe.

Thoughts?

 

The Magnaflow's are cheaper than OEM's and are going to have to be done by a pro, like the OEM's. So it's either spend a ton of money for OEM junk cats, or spend less for awesome cats, take your pick.

 

Not at all expensive. http://www.summitracing.com/parts/MPE-94306/

OEM cats are $300 each.

 

These cat assemblies are $300...
http://www.autopartswarehouse.com/sk...%26+Drivetrain

This is what I am wanting:
http://www.autopartswarehouse.com/sk...%26+Drivetrain


Don't the "universal fit" cats usually require welding? I have a welding rig in the farm shop, but I'd much rather use U-bolts.

Are the high flows really that much of an improvement over a standard? I am not willing to spend nearly twice as much to gain 0.5 HP.

It maybe helpful to know that I run an Evo on Level II.

 

Why would the OEMs require professional install? Isn't as simple as removing a couple U bolts?

I was under the impression that the "universal fit" cats required welding, but the OEMs did not.

 

OEM cats are welded inplace in the pipes as part of the Y pipe. You can get universal cats such as the one I already showed you, and they will work, they will require a custom fabbed fit, you can clamp or weld, much better off welding to reduce leaks.

 

http://www.performancepeddler.com/pr...CT_ID=MAG94006

$120 for both cats

You're going to have to weld it all up no matter what. U-bolts leak, welds don't. These hi-flow cats give you more torque, power and sound.

 

Could you expound on this? How will I know if the pre-cats need to be replaced? Are you saying leave them be if the pre cats are fine, or delete them regardless?

Will deleting the precats trip another trouble code? Will I need to have my Evo conveted to a Gryphon and get custom tunes to compensate for the deleted pre cats?

Currently I live in FL, but after graduating in Dec I will be moving back to the north east, most likely western NY. Will deleted pre cats pass the state inspection?

 

Its best to run only two cats if you can get away with it. But if you legally must run 4, leave the OEM pre-cats as is since they do not resonate sound badly or kill flow, and replace your rear converters with hi-flows. In NY I know they are pretty serious about inspections and such so I'm not sure if you can only run two. Front tinted windows pisses NY cops off even.

 

No, as long as you have a cat on there, you should get no codes.

As long as you have a cat, you should pass any state inspection.

 

Well, I found a set of Magnaflow 94036 for $116.60 shipped.

I'll leave the pre cats on to cut down on the labor. I'm not looking forward to having to get under there with a MIG welder when I don't have a lift, but I'll be glad to get rid of the rough idle and get my mileage back to normal.


Thanks for all the help.

 

Sweet deal, very fair. Goodluck with the install, make sure to have a couple good sawzall blades for removing the OEM cats and take good measurements.