Since I am digging into fixing my 99 F150, 5.4, I thought I would look at some modifications that would improve mileage/performance. Getting more air in and out seems like a good place to start.

I am looking at a CAI of some sort, I have been just running a K&N filter. How much of an improvement could I expect?

Of course, with more air getting in, it would be nice for it to get out easier too. Herein lies my can of worms. Lots of folks on here talk about removing the second set of cats. Does anyone know if that is legal here in Oregon? I would hate to make modifications that end up being a big no no!

And along those lines, are there recommeded ways to go? I am not looking for some specific sound (but I dont want it to sound like crap either), just better performance.

Also, are there any other recomendations that anyone has that would help out with the mileage/performance issue?

Thanks
RJ

 

Not a can of worms at all, just another good topic for this section!

I've come to the conclusion that most all CAI are more or less the same. There's even an intake you can build in about an hour for only like $15. Just look up the Gotts Intake mod. You can still use your K&N filter and it will perform damn near the same as a $300 kit.

The cats on the other hand are good to remove, the second set that is. As long as you have a set on there, you should still pass the test. I would also do a simple muffler swap, like a Bullet, Magnaflow, Borla, or any other "straight through" muffler.

On a side note, you won't notice hardly any gains until you get custom tuned for all these new goodies. The stock programming can't take advantage of the new parts on its own.

 

id hack the cats off and put on high flows.

 

Both sets? In Oregon we dont get smog tested or anything, but like I said, I just wasnt sure what we can and cannot do in this goofy state.

 

Removing rear cats will cause you to fail on the Smog and sniffer test, too much carbon is passed without being filtered. And depending on your area if it comes with 4 it will need 4 to pass. Thats how it is here. Your best bet is going to an exhaust shop with young employees that know the law, but also know what you can sneak away with. You could possibly get your rear cats hollowed out, give them the platinum and rhodium inside them, and they will feed pipe through them and put them back in if you dont need the smog test, that way you have a better flowing system, and a little more growl.

An enclosed intake is always best for performance since it draws actual fold air in from the fender like the OEM intake does. And open filter such as K&N will only draw in air from the engine bay and partial from the fender.

And if you do not have a cat-back of some sorta already that will gain you at least 0.5 mpg with a direct flowing muffler.

After all of these modifications, if you really want to get good economy and performance, look into the custom tuners to unleash the hidden power from factory tuning, and tune in your intake and exhaust work to perform properly. You can expect atleast a 35 horsepower gain and 1.5 - 2mpg gain from all of that.

 

do the gotts mod on the intake

 

agreed wit Jerame. best intake for the $$

 

i guess if you have to replace the rears with high flow cats and leave the front factory ones on.

 

I am going to do the Gotts this weekend. that seems like a pretty easy choice.
If I was able to put together a couple more mpg's, I'd be happy.
I am now thinking of removing the rear cats and maybe going with a flowmaster 50 or a comparable magnaflow. I am looking for something deeper, a bit of a growl, but wont be super loud in the cab.
Is there comparison of the difference mufflers, including what types of change in sound you would expect?

 

Magnaflow 14" si/do

Part # 12198

 

Basically all Flowmaster's drone. A SIDO Magnaflow won't drone nearly as much, but you can always go for a longer one.