Exhaust question?
 

i have a 94 f150 5.0 2wd wanting to know a good size diameter for exhaust pipe 3 or 4 inch?
and does what is a good brand for a catalytic converter?

3 in, you still need a lil back pressure to run correctly

I would say for a stock 5.0 stick with 2 1/2"

Matt

no bigger then 2.5 unless serious engine mods are in your future plans.

Are you talking about single or dual pipes? I would say a single 2.5 or 3 inch and for dual pipes go with 2.25.

Magnaflow makes good replacement cats, so does Catco. There may be better ones, but these are better than most.

I don't think i have the money for a dual, going with single and just wanted to make it rumble a little louder!

Ditch the muffler and just run the tailpipe off the cat. That will make it louder. They make cat back systems that basically do that.

Kinda like top of this page:
Truck Parts and Truck Accessories

Kinda pricey, but you could have something made up yourself.

my buddy has a 1986 f-150 single cab short bed and all he has done for the exhaust is put a flowmaster 40 on the cat and turned it out before the rear wheel. now thats an awesome rumble!

Don't go any bigger than 3" behind a small block gasser. But 2.5" duals would be plenty, and a 3" single would be just fine too. With big pipe like 4" you lose a lot of the scavenging that you get with the smaller pipe. But too small of pipe and you create back pressure, which you want to eliminate as much as possible in a gasser.
If you don't get smog tested, you could just cut the cat off and run a flowmaster or similar muffler. I'm kinda partial to Flowmaster mufflers, but whatever your preference is.

just did a 2.5 " Magnaflow on mine also with a new cat from Magnaflow(A.K.A Carsound) .Sounds nice and quiet at idle but when you get on it, gets nice and throaty!
runs alot better too.
Single exhaust out the back

I had an 4x4 1985 5.0 4-spd manual, that I cut the cats off, and put 2.5 duals with glass-packs on. Cost me about $200 out the door.

The exhaust in the truck im getting rusted off at the back of the cat, Im keeping it short sweet and simple! walker dual into one universal cat into a cherry bomb extreme muffler with a 12inch turn down out of that, pops out right before the rear axle. everything is ganna be 2.5 inch tubing