It's easy to see why the Gibson Cat Back
improves performance, sound and gas mileage!

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Its job is to measure air flowing into your engine, this Mass Air Flow Sensor from Granatelli Motor Sports will increase flow as much as 47%!

   When you install the K&N you have to R&R the mass airflow sensor as a matter of course, so now is the best time to maximize your intake with a new high performance one.

   If you are new to tinkering with EFI engines you may be unfamiliar with what this component does. In a nutshell it measures the raw volume of air that is being sucked into your motor. In combination sensors that measure air temp and barometric pressure, the computer corrects for relative air density (RAD) and calculates the precise amount of fuel to inject for optimal air/fuel ratio at any speed, gear and load condition.

   An OEM Mass airflow sensor typically flows fewer CFM than the throttle body and is  now the bottleneck in the system, having removed the airbox and restrictive intake snorkel. By opting for a larger, more freely flowing  (+47%) unit we now have the most air being delivered to the motor we can. The only step up would be to a costly cold or "ram" air or extremely expensive forced air such as blown or turbocharged induction systems.

   Granatelli is a name that is as old as auto racing itself and offers the highest quality sensor for  most common applications. Their mass airflow sensor is easier to install than your key in the ignition and should be done in conjunction with the K&N to get the best bang. Also since you have to swap in the one from your stock airbox anyway, installation time is actually reduced.

   Horsepower gains at the rear wheels of 10-15 hp, better throttle response and fuel economy , "no-brainer" installation and 50 state emissions legal makes it obvious why the Granatelli mass air flow sensor was chosen to help us get the best bang for our buck.

The new Gibson "Sport Truck Exhaust System" installs, sounds and fits like dream. The twin stainless exit tips make for a super clean and business-like appearance.

   It ain't enough to just stuff more air in, you gotta get it out too. For our exhaust  removal chores we turned to Gibson Performance, a family owned and operated company in Corona, CA. Gibson is known everywhere for manufacturing the highest quality exhaust systems. We used their brand new Sport Truck Exhaust which is a one into two "Cat-Back" system that dumps spent gasses through twin tailpipes just behind the rear wheel.

   Manufactured from mandrel bent aluminized steel it replaces the puny OEM system from the catalytic converter back to the tailpipe with a single 2 1/2" pipe feeding into the new Gibson high flow muffler then exiting into twin 2" stingers with polished stainless steel tips. (It is against Federal Emissions Laws to remove or modify a catalytic converter). Mandrel bending means that all curves retain the exact tubing diameter, unlike OEM systems which are built of smaller, inferior quality tubing to save money, and are crimped at each bend causing restrictions to flow and pressure waves that rob horsepower.

   The aluminized steel exhaust provides superior corrosion resistance to the factory system and is backed by a "Lifetime Limited Warranty." This construction is more than adequate for a lifetime of use in drier or more temperate climates. In the desert it will last forever. Although those readers that live in areas where the roads are salted in the winter or in wetter coastal regions should consider the spending the extra bucks (probably double) for an all stainless steel system.

   The engineers did their homework on the sound. With a deep, but mellow rumble the Gibson system delivers a pleasing, if not exhilarating exhaust note. Almost no increase in interior noise was detected while those that are eating your dust will certainly hear you as pass by. The exhaust note is perfect for 99% of those drivers out there looking for not just the feel of more power, but the sound of it as well. Only hardcore sound junkies that crave the thunder of burnt out 'glass packs will be left unfulfilled.

   As to power, expect real world increases of 10-20 horsepower at the rear wheels dependent on vehicle equipment and tires/gearing. As well as improved economy and a kick ass sound. Another bargain in the quest for more power!

   Installation of the exhaust is also a snap for an intermediate mechanic. While some more specialized tools such as a SawzAll for removing the old muffler and an oxy-acetylene or wire feed welding rig for tacking the new pipe joints are needed. The system fits perfectly and should take less than two hours to install.

   Overall we rate the Gibson Sport Truck Exhaust System as excellent and the perfect compliment to any truck! Finishing Up

   With all the performance mods completed we took a long hard test drive, while it will take several hundred miles for the computer to recalibrate to the changes fully. The difference in performance was noticeable, even with the enormous tires and greater wind/rolling resistance we can pull a stock Expedition to the next stoplight by a car length. While no dyno tests have been done yet, I would estimate the modifications have yielded an increase of approx. 40 horsepower. With observed fuel economy dropping from an original average of 14 mpg to an average of 12 mpg. Most of this decrease is due to the higher vehicle profile and that giant spare pasted on the roof rack. With the spare removed, fuel consumption returned to about 13.5 mpg.

   Was it enough of a bump in power? For me, no. I'd like to get another 50 horsepower or so to the rear wheels to give me a chubby. At freeway speeds of 75-85 the BFGs beg for more, the chassis/suspension is confident, but the drag of the increased weight and ride height means a downshift into third on steep grades or against strong headwinds. In wrapping it up we'll add a set of Gibson's headers and hopefully find a prom chip for this application. Unfortunately at this time their are few chips on the market for the 5.4L Expedition and none we felt would fit our needs or provided increases in performance that justified the cost. There are several however for the F150 that are excellent, such as the Hypertech Power Programmer III. We are researching this chip to see if it can be applied to the Expedition, but at press time had no data.

   Come back next month when we go over the extensive exterior modifications made to the Project Baja Expedition!

Click Here for Page One of the story!

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Performance Products
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Rear Window Spoiler