Hello, I have a beautiful 1994 F150 XLT Extended cab with a 351 Windsor High-Output engine in it. It has 170,000 miles on it and the engine runs real good for having that many miles on it. I am restoring or say "touching up" things here and there. The truck is in REAL good condition. What I want to do is run true duals from the manifold back. It's got stock Y-Pipe adapter on it right now and into one small pipe.. Headers aren't an option right now... I don't want some cat-back crap. What I want to do is take off the stock muffler and cat and put on pipes from the manifolds to an X-Crossover adapter, then straight pipes to thrush mufflers and out the back. Make my girl purr real nice like! Except I have one problem... The diameter of the output from the exhaust is different from the diameter after the Y-Adapter and the diameter is also different after the cat!!! I'm soo freaking lost it ain't funny! What is the stock size of pipe after the manifolds? I need to know what size that is so I can order the correct parts. All comments and suggestions are welcome even for different setup suggestions!

 

my f 250 with the 351w has 2 1/4 OD colectors off the manifolds and i have that running true dual all the way out the passenger side in front of the rear wheel

 

There is no 351HO in this vintage truck, are you saying you or a previous owner swapped in a carbed smog motor from the mid '80's?

I also don't see why you're concerned about the diameter of the pipe on the stock exhaust, you can't use any of it with duals so you can select any diameter you like though 2-1/4 is plenty for a stock motor.

You won't find any direct fit X or H pipes for this truck either and parts from a Mustang won't fit due to the location of the gas tanks and 4wd components if so equipped, so you're gonna be fabricating this system from scratch.

 

I don't know what all is different between my '89 and your '94, but I used this on mine:
Truck Parts and Truck Accessories
(it lists 80-91 std cab only). Could likely modify it to fit your truck.

It runs both down passenger side to get away from tanks, then jumps over rearend to get left side pipe out. Looks very nice, not like every other typical dual exhaust with pipes out under bumper(I hate those).

I did have to "finesse" it to fit better. Seems they missed the front bends a bit on left side. Nothing a welder couldn't fix! Not bad for $200.

 

The owner (person who purchased it new) specifically ordered this truck to have this engine in it. He used it to pull heavy trailers. Don't know why he didn't get a 3/4 or 1-ton truck... Anyways, It's got the Windsor High Output engine in it believe it, or not. I'm not concerned about the pipe size of the stock exhaust. I'm trying to get the exact size for the manifold outlet. And I also have found some X crossovers for my truck. It's more of a universal product. It just depends on the size of the pipe you use it with. No 4WD, just 2-wheel drive with a towing package. @buzzy613 - I might just have to go out the side in front of the wheels.. That's a good idea!

 

If he purchased it new, it still isn't an HO motor. Period.

The only HO motors would be a swap. Being an HO doesn't even have any real impact.

 

Oh, Nice... Guess he did do a swap but did all the paperwork along with it. And I didn't think it had a big difference from regular windsors. But it sure is nice! Who wouldn't like it? But the gist of the question is that the output diameter of the manifold is in fact 2.25". If that's what it is, I'll order the parts now. And you can always get couplers that go up or down in size, right?

Had a better idea: Why not just forget the X-Crossover, and just get a single muffler that has 2 inputs and 2 outputs??

 

On my 302 Bronco, I ran Pacesetter Headers into a Catco y pipe(it never merged) into a universal x pipe then exited before the rear tires. It was straight piped xpiped duals.

https://www.ford-trucks.com/forums/8...r-351w-ho.html

https://www.ford-trucks.com/forums/1...d-351w-ho.html

 

with my custom 4 in tips it looks like 2 mini cannons out the side lol and when i get on it sounds like them too