01 7.3 CC 4x4, 4" lift, 16.5x35x12.5, 3:73 gears, 4"MBRP exhaust DP Tuner and my last 1,000 mile all highway trip (relatively flat ground) avg 18.9mpg. This was according to the trip computer. I have had the odometer calibrated for my tire size. I'll start checking mpg at the pump on paper. I honestly don't think you're ever going to see 20mpg unless you stay with stock tires and height.

18.2 at 75 to 80 towing an enclosed trailer (7x14) with 3 full dress Harley's in it. Dropped to 16.5 with the wider tires/rims, same trailer, same bikes, same driving speeds.

Yes! that is what i did.

Simular to putting a super chiller on a blown motor using water for coolant.

2001 F350 Duely 4:10 rear end 16" tires not 4 wheel drive and yes that is calculated by hand.

Anybody got any good results from just taking the muffler off of a stock exhaust system?

Are you smoking crack?:cool-smiley-027: How loud would that be?

My Excursion is running with muffler delete. It doesn't make all that much more noise than with it on except for a slight increase in resonance. The stock muffler is EXTREMELY restrictive, and the muffler delete will drop the EGT's significantly. I've never calculated what the increase in MPG would be.
Those who don't like running without the muffler commonly add a Walker BTM (Big Truck Muffler) after removing the stock one. They are available at many parts stores- Summit Racing has them as well. Less than hour at a reputable muffler shop getting it welded on, the cost of muffler and install should run you right around $100.
Jim

I went with the magnaflow 4 inch system, with 3.5 inch down pipe. 409 stainless just under 500 dollars.

Zero power increase. Zero fuel mileage increase. HUGE drop in EGT's.

I hate the sound of 7.3's with out mufflers. Because of the firing order and piping, they flutter, and sound like crap.

Buy an exhaust system. A must for a drop in EGT's with a chip.

I've got the 4" MBRP with dual exits behind the tires and 5" cans/tips on mine. I did chip, intake, exhaust, and gauges all in one shot, so I don't have any comparisons.

But it does run like a scalded monkey when I ask it to. OutlawMark here on OSO did all of my upgrades ( www.lightning-motorsports.com ) when he ran a shop here in Virginia. He has worked on countless trucks, and said that my combination provided the fastest stock turbo 7.3 that he had ever driven. (If you notice on Mark & Tom's website, they both drive 7.3s with mods. They know the trucks well.)


One note... on my 7.3 Auto 4x4 CC Dually (with factory 2" blocks, not 4") we could not get the 4" exhaust to stop smacking the transmission crossmember under acceleration when the motor torques up and the rear stays planted. You have less than 1/2 inch of clearance through the hole it has to pass through. I ended up padding it with a thickness of high temperature silicone radiator hose, and now I don't have anymore thump. This is a common problem reported on TheDieselStop.com. Other guys banged a dent into their long pipe to combat this problem, but I just could not see doing that.