everyone's lying, its totally accurate. now you can feel good about it again.


hope that helped, hah.

 

How did you not get run off the road?

Best tank ever was 19.5, but it was hard... I usually can get 16-17 average combined. If it is just to and from work it is 12-13 mpg.

 

Don't race every numb skull from the lights. I drive easy, but I don't drive like grandpa either. I drive ~20 one way to work each day averaging 45mph, but very little stop and go. And I try to keep it around 65/70 on the highway if I go anywhere. This is on the E10 crap the stations are starting to use. When I could still get 100% gas I was getting 18.4mpg.

 

if anything the mileage calculated through the ECU/ECM should be more accurate then your own calculations. the ECU/ECM should be calculating the mileage based on knowing the size of the fuel injectors(constant), the measured fuel pressure and the measured fuel injector duration. It then compares those values of fuel consumed to the miles driven. The error in that calculation would then be the changing of the diameter of the tire due to change in tire air pressure and tire wear, which is why your speedometer and odometer are not 100% correct.

When you do your own calculations how to do you know you are filling the gas tank to the same level each time? The only way to know for certain is to completely top off the tank to the point where fuel is pouring out the side of the truck.

Anyway, back to the OP, those are some nice numbers. The best i have done in my 5.4 screw is 18.7 and i average about 16.6 with mixed driving

 

My gryphon read a best of 20.2 mpg coming back from orange county, ca, to las vegas.
First quarter tank wasn't as good as usual on the way back but managed to go 290 miles on half a tank of gas: I have the 30 gallon tank.

List of Mods:
Gryphon on canned 87 tune
OBX Long Tube Headers w/resonators
Ebay X pipe
18" dynomax bullets
4x18 tips 45'd out the back
35" toyo m/t's on 18" xd diesels and a 2.5" HBS leveling kit

I was traveling at 75-85mph and my speedo is accurate as is the gryphon. I'm still on stock 3.73 gears, having the fx4 and just had her in for 30,000 mile service, which helped a bit. Ever since installing the long tube headers I've managed to get about 150-180 miles per quarter tank on the highway.

Currently at 360 miles with a quarter tank left. 300 miles highway and the last 60 has been city only with a few spirited runs.

Electric fans go in this week sometime and I'm hoping for another mpg or two both city and highway, some pulleys might be in the works and eventually 4.56 gears front and back.

The gryphon isn't exactly an average mile per gallon read but more of a the fuel injectors are shooting in xxx of fuel per mile and that's what your average is at this moment if you continue at this speed on this course type of deal. It takes in 100,000 readings and is usually pretty accurate to within a mpg or two.

Custom tunes, fans and pulleys, should see me around 22 mpg highway

 

Where did you get the headers? Easy install? How much? Would that mate up to the Roush Off Road exhaust well? How do they sound/what is the change on the sound profile?

 

http://www.sparktecmotorsports.com/f...t-headers.html

That's where i got them from. Had them shipped to me for $500 within a week
Danny is a great guy, definitely helped me with all my questions and worked a steal of a deal for me. They also offer high flow cat versions for i believe 100 more. Definitely worth every penny.

They are a replica of the dynatech longtube header kits that go for roughly 1200-1400.

Install on my fx4 was a pain in the it took longer to remove the stock manifolds (for sale) than it did to put the headers in (5 minutes)
I ran open headers for a day, sounded like a v8 speed boat

It will mate up to basically any 2.5", (ideal for true dual exhaust for peak hp and deep sound), y pipe setup, or you could go the true dual route (which i highly recommend). At idle, if you've ever heard a turbo diesel boat at idle, sounds deep, aggressive and can be heard from pretty much anywhere. Especially in cold weather.

During the mid summer heat in vegas, i could park my truck about 100 feet from the building, go inside and still hear it at idle. Awesome if you ask me.

Wide open throttle it's like an orchestra of the muscle these 5.4 v8's can produce. Can get a little raspy, but when there's tunnels, walls, hell even other cars next to me, the echo is just breath taking, brings a smile to my face, the mrs. face, my friends and occasionally the people i scare the out of at wide open throttle.

Sometimes if you let off at wide open throttle, say 5400 rpm and you let off the gas right before it shifts, it sounds like a mustang with some serious power and exhaust upgrades. People ask me about my exhaust all the time, it's fun to talk to them about the truck and I've steered a few people towards Danny. Customer service is excellent and prices are to die for!

No magnaflow, slowmaster, fartcan etc; can replicate the exhaust note produced. If you think a chevy or dodge is loud, mine is louder

If you have the lightning style exit, out the side before the rear tire, it will be louder! and drone like hell.

All in all i spent roughly 750 before install
OBX Long tubes-500
X pipe-40
dynomax bullets-60
tips-60
bbk extensions-80
o2 bung plug-4
02 gotts mod-7

Had a local mechanic out here install the headers for 225 for 3 days work. A great deal if you ask me. Welding the kit together was probably about 2-3 hours labor if done correctly but your roush kit i assume will bolt right up to the obx kit, as long as it's 2.5" pipe

2.25" is optimal for torque but if you plan on a turbo or supercharger, go 2.5 or 3" but id stick with 2.5" if n/a

If i had to do it again, i would i love my truck and definitely a great upgrade if you plan on doing a full exhaust.

You can always opt for this setup however if on a budget:
2 magnaflow 94106 high flow cats
ebay x pipe or magnaflow x pipe
2 dynomax bullets/magnpacks (12" if no headers, 18" if headers)
2 4x18 tips

It will be deep, growl and is the cloest sound to long tubes you can get

I noticed an increase in mpg to top it off, extra 2mpg highway and my truck is 7200lbs from the factory before my 35s 18" diesels and myself

I average around 12-16 city depending on traffic, my right foot and 17-20 highway depending again on traffic and my right foot, cruise control is the way to go but i guess cruise at 80mph is why i only get 20

hope this is more than enough information for you and to make up your mind on the headers

 

How do you like the Bullets? I've got a glasspack right now and want something a bit louder.

 

the bullets are great, straight through design, basically like running straight pipes, but if you want loud, go high flow cats, 12" bullets and two 4" tips of your choice

performance peddler has the cats for about 96.00 with clubgp as the code

the bullets you can get on summit for i believe 60-80 for two.
a great alternative and probably a better one, magnapacks, same design but a little better sounding

 

I already have the exhaust on. So I would need the Long tube headers and what else? Looking at the no cat version... I assume the current cats would be used?

Not sure I have the $$ to replace the cats...