5.0 Mustang & Super FordsHow To Engine
Installing and Dyno Testing the MBRP After-Cat Exhaust
The continuous research we do with '11-'14 Mustang GTs has proven that Coyote engines thrive on airflow. Yes, we've seen mild-to-wild performance gains when air to these new bullets is improved with intake systems, power adders, and freer-flowing exhaust systems.
The exhaust side of Mustang performance is our focus this month, and with the help of Ricardo Topete of GTR High Performance, we're installing MBRP Performance Exhaust's all-new, 3-inch Street Series after-cat exhaust for '11-'14 5.0s (PN S7258409; $719.04). We will evaluate the bolt-on system's sound, and of course, the impact its 3-inch tubes and high-flow mufflers have on performance. MBRP claims this system adds approximately 3-5 horses at the feet. When you consider the fact that the MBRP after-cat system flows an additional 100 cfm over the 2.5-inch, resonator-choked, bend-heavy OEM tubing (604 to 502), a gain of some sort certainly is anticipated.
Freddy Contreras provided his ridiculously fresh '13 GT for this experiment. The Pony was completely void of any other mods, and weighed-in with baseline peak power (366.07) directly in line with the rear-wheel steam of other stock Coyotes we've worked with.
Check out the photos and captions for the details on MBRP's updated Coyote exhaust pieces, and a few quick highlights of the after-cat R&R procedure. The effort does qualify as a 1.5-hour DIY. However, as Ricardo demonstrates, that's only if you have the facilities and equipment necessary for this type of under-car operation.
On the Dyno
Having performed baseline dyno tests on Freddy Contreras' new '13 Mustang GT at the outset of our project (and logging the 'Stang's anticipated 365-367 horsepower in stock trim), we closed the evaluation with another round of laps on the Dynojet's rollers to compare performance and exhaust-sound differences with MBRP's 3-inch Street Series after-cat exhaust for '11-'14 5.0s (PN S7258409; $719.04) installed.
First we have to say, the aural change this setup makes on a Coyote's exhaust note is awesome. At the crack of the ignition, the Street Series high-flow mufflers sound great—mellow, but also pleasingly aggressive, and (in our opinion, as well as others who were present at the dyno session) indicative of the way '11-up GTs should sound from the factory.
As for power-at-the-wheels, the exhaust upgrade feted us with nearly 6 extra horses at the feet of Freddy's Pony, in accord with MBRP's claim (a little better, actually) and without PCM manipulation via custom tuning.