I have a 2002 5.9 cummins diesel..i have a juice with attitude chip..cold air intake and a straight out exhaust...what would help me maximize my fuel mileage and horsepower?

 

The only thing I could suggest is using Drew's brew. I have a chip and cold air intake on mine and my truck runs much better now that I'm using the mix.

 

Keep the boost as low as possible, like under 11 when driving. If you do this you will notice the truck will continue to accelerate just not at break neck speeds. Keep your foot out of it. Good luck with that one.

 

toss in some 50hp nozzles on the injectors, should gain some mileage and added HP.

 

This would be the best route. Some mild injectors. BUT, if not already done, put a lift pump on it, like an AirDog or FASS...injectors equal better atomization. Dont drive by the boost gauge; just go light on the throttle. Use cruise on the highway. If you have bigger tirs, maybe go down a size, or even to stockers. If its lifted, ditch the lift. And I say this as Im looking at going 4.5" and 35 13.50 20s...and Im not exactly light on the pedal.

What the h*** is Drews brew?? Apparently some fuel mixture. I wouldnt put much into that, but hey, sometimes crazy things happen haha

EDIT: Found Drews Brew...hmmm. It might work. Never tried anything like it, but Ive never put much faith in them either. Give it a try and see what it does...

 

to maximize fuel mileage you need to increase your low end torque w/o using any more fuel... this is done by changing the exhaust and intake setup. open both ends up and your top end will scream but your bottom end will suffer. close them up some and you get more low end torque but the top end will suffer. your best bet is to determine which is more important to you and go with the setup that achieves that goal. OR... you could go with the open'd intake setup, AFE Stage 2 w/pg7 filter or something like that and get the exhaust setup so you get mileage out of it, then add an exhaust dump to it. quicktime has a remote controlled one, install that or something similar and then from inside the cab, open it up when you need it.

if your really motivated you could create an active exhaust that does this automatically based on throttle position...