I've been thinking of cutting off the rear catalytic converters and replacing them with empty pipe, or leaving them on and removing the inner pellets. I'm all for keeping the air clean but I would rather just have 2 catalytic converters instead of 4. I did some searches and some people say they improved gas mileage by doing this by 2 miles per gallon. Is there a preferred method of doing this? I called a few shops, and they won't even weld in pipe if I cut the converters off myself. Can I just clamp on pipe sections? I was also wondering can I cut out the factory Y piece and clamp on a better flowing replacement Y piece?

 

Just because the truck has 4 cats does not mean they all do the same job. There are 2 steps cats follow doing their job. Step one is reduction of emissions( front cats) seccond step is oxidation(rear cats) so if u remove one set you will be removing one half of the process. Not to mention pissing off your computer beyond all recognition. I would reccomend looking into some high flows from magnaflow that incorporate both stages in one cat so you would only need to install 2 they run about $90-$130.

 

I used to have a 2000 Mustang GT that I had a catalytic x-pipe installed on without issues..was that because they were the 2 step converters? Is there a 2 converter high-flow kit that will just bolt-in between the headers and muffler, like on the Mustang?

 

Ok, I have done a lot of searching and researching and I get conflicting answers. I am just trying to figure out what mods are most important, in what order. Especially, best bang for buck power and fuel economy. I have talked to a local performance shop and the owner there claims that the very first and best thing I can do is get rid of the cats and put in 2 high-flows. Then he says intake, tuner, throttle body, headers, lower gears, maybe e-fans and maf way down the road. He also claims that underdrive pullies would be worthless for me because they only help at high rpms. Any imput on this would be appreciated. Let me know if you agree with his ideas and if not, please explain.

 

^ Let me make this simple for you. If you want your truck louder, then change the exhaust. If you don't want it louder, then leave it alone. The money that you will have into it will not justify the minute increase in HP or MPG.

Under-drive pulleys do help in the low-end too, but again, not really that much of a difference. The best thing you can do to save fuel is to drive smooth. No harsh acceleration and braking. The second thing is to drive a little slower! It would surprise you how much fuel you would save by lowering your speed by 5 MPH on your daily commute. Now if that isn't enough, then by a car.

Now if it's HP your after, then buy a blower or a sports car! haha

 

I agree with av, drive slower for mpg's. Hi flows for sound

 

Sorry to hijak this thread! I didn't even mean to post that here! I posted a new thread of my own here: https://www.f150online.com/forums/ex...-03-5-4-a.html

 

Not sure about inspection laws in new york but in PA if you cut off a cut and put on a straight pipe that is illegal.

 

It makes me nervous to do anything with the catalytic converters because of inspection, and I do like a quiet exhaust. I like the idea of adding pulleys because they free up about 10 horsepower and ft. lbs. torque. That's not much by itself, but it adds up with other things such as the performance tuner and muffler, and better flowing air filter. I like doing things to add horsepower, it's fun for me. It's not an option to supercharge because I can't afford it, but I've been looking into adding electric fans. If I can get a performance shop to do it and have it be problem-free, I'm all for it. if I get those two things done along with what I did already, that should be equilalent to 50-60 horsepower. Little things add up nicely.

 

Now that is a legitimate reason right there. The reality is that 20 HP is not felt in a 7000 pound pick-up.

 

Well I don't know about that, adding the performance tune was definitely noticeable and that is supposed to add 15 or 20. I don't have the heavy duty 150..I thought they were 4600 and change according to a lot of reviews I read.

 

Every time I go to the local landfill, the scales hovers around 6000lbs depending on how much gas and such. Thats leaving too, so the bed is emptied out. 04 supercab FX4

 

Let me guess..supercrew? 2004 models are heavier to begin with, but even then they are still less than 5000 if you have a regular cab. Mine is a 2002 regular cab, so that's why it's not so heavy. Of course there is the added weight of tools if you have them, and also gas and whatever you're body weight is.

Ok I just re-read and saw you have a supercab, but even so, they are still heavier.

 

you can do electric fans for under 200. get a mark VIII fan or mustang GT fan and buy a reliable controller.

 

^^ This. First.




And - either leave the cats alone, unless they are plugged, or replace with the proper Maggie hi-flows.

Stay legal - it's a Federal offense - so that's ALL states, for the rest of y'all ...

MGD