Gentlemen & All Others ,
Speaking from personal experience, does the Borla Exhaust System improve performance and GAS mileage on an 04' Disco? How about the addition of a performance air intake? Please only reply if you've been there, done that, and got the T-shirt! Thanks!

 

With the $900 plus you would spend for the pair, you might see 1/2 MPG increase at highway speeds, little in town.
What sort of mileage are you getting and what have you done to try and improve it?

 

I have a borla and have installed a fancy cone filter to See what it did.

The borla is all sound, it makes you feel like you have more low end torque but I doubt there is an increase. The intake may give you a tiny bit of power. You can literally feel your engine sucking in more air when you hit the gas. But those intake and special filters allow A ton of dirt inside the system. I love my borla and I am using a standard air filter. I'm not going to sacrifice my MAF and the clean air that enters my engine just for a little bit of increased acceleration.

I haven't noticed increased mileage with neither. But I have a lift, big tires, and a roofrack... It has always been around 10-13 mpg.

 

I'm getting 11 MPG around town right now. I'm also using a K&N air filter. Not one of the cone ones but the one that's made as a standard replacement filter. It sounds like it wouldn't help me with gas mileage to upgrade the exhaust and from what I keep reading there seems to be some unhappy people with the K&N replacement filter??? To much unrestricted air flow allowing dirt through the system??? I'm not an off roader and I don't live in a dusty environment. Should I be concerned about this?

 

Yes, yes you should.
Dusty conditions or not you will still be sucking in dirty air, smog is just as bad as dust.
Go back to a paper air filter, buy it at AutoZOne, Wal-Mart, NAPA, O'Rielly's, where ever you want.

 

There are people running them, and they get really upset about others saying not to run them. I ran one in mine, but after seeing how dirty my intake got, I would suggest not running a K&N. The MPG gain you may see will not be offset by the cost of a new MAF. The Bosch one's on a D2 are very sensitive.