Project F150: Part One – Opening Things Up With a MagnaFlow Exhaust System


Howard uses a scissor jack to carefully align the final section of our new exhaust. The MagnaFlow system uses slip fittings, so you have quite a bit of room to make some fitment adjustments.


Let's talk power! Our first set of runs established our baseline. The F150 made 256.9 HP and 339.3 LB/FT TQ at the wheels. If those numbers seem low, remember that you cannot compare dyno results from different systems or even different days.

Long term readers know that we like the SuperFlow dynomometer for its ability to better replicate real-world driving conditions through load generation. Remember, the most important thing is the difference between each before-and-after run. Not the peak numbers. 


Here we have our baseline power data (MotoIQF1503) versus the power with the MagnaFlow Four Inch Exhaust system (MotoIQF15016). The odd spike and dip before 2,500 RPM is a result of the vehicle coming off of our load generator. 


The results with just the MagnaFlow 4″ exhaust system were quite good! As a comparison of peak values to the results with the stock F150 exhaust, we saw gains of 17.3 wheel horsepower and 12 foot pounds of torque!


Dyno runs were made to establish baseline horsepower and to measure the gains made with the MagnaFlow four inch exhaust system, but we also made some bonus runs to show you what a simple tune can do when combined with a large diameter exhaust system.

The folks at 5 StarTuning caught our attention since they create a bespoke tune for each customer. You just visit their site, tell them about your rig, and you'll receive your tunes by email! Many popular handheld controllers are supported, including our SCT X4.

We started modestly with their 91 octane map. If you're worried about what happens when your truck is under full load — like towing on a hot day up rolling hills, they have that covered too! We chose an especially conservative 87 octane “tow map” for such purposes (but always use the best fuel available for cheap insurance).


Our F150's run with only the MagnaFlow exhaust system (MotoIQF1516) versus the run with the MagnaFlow exhaust and the custom 91 Octance Map tune from 5StarTuning (MotoIQF1506). Combining the 5Star Tuning map with our new MagnaFlow exhaust yielded an additional 20.1 horsepower and 16 foot pounds of torque. 

1 comment

  1. Curious – I just installed the Magnaflow 4 inch exhaust on a 2.7 and got a couple overboost codes when in tow mode. The truck is not tuned. Funny thing is I just replaced a 3 inch on same truck and it seemed to be more powerful. No dyno no tune just wondering if you have any thoughts or advice. The muffler on the 4inch MF system is way too loud for me. LOL

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