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Late model 5.7L Hemi Mopars are a blast to drive as they come from the factory. But you and we know that they can be made even more fun. Getting more horsepower out of a given engine is a function of moving more air and fuel through that engine. In order to get more air into an engine, you have to be able to get the additional air out of the engine. That’s where exhaust upgrades come in.
A lot of mods that were worth a bunch of power and torque back in the day aren’t worth much in today’s computer controlled EFI cars — they’re just too efficient. But the rules of internal combustion engines haven’t changed and if you can get more air to move through an engine and add more fuel to match that air, you make more power. So we wondered what a good old fashioned full exhaust system upgrade would be worth on a late model 5.7L late model Hemi.
We lined up a 2009 5.7L Challenger that still had its stock exhaust system in place and had a cold air intake. The CAI would ensure that any increase in airflow out of the engine would be matched with extra air flowing in as well. The car is owned by James Nunley who is a Mopar fan and knows a thing or two about driving — he’s an instructor for the Los Angeles Sheriff's Department Academy and teaches high performance driving at the sheriff’s facility at what used to be March Air Force in San Bernardino county in Southern California. JBA Performance Exhaust set us up with a set of their silver ceramic coated Cat4ward shorty headers (part number 1964S-1JS), high flow mid-pipes with catalytic converters (part number 2965SYC) and their 3” cat-back exhaust with mufflers (part number 40-1666).
We also talked to Diablosport about a hand held programmer for the car. If you’re upgrading the exhaust system and increasing the air flow through the engine, the stock computer programming may not be optimal for maximum power production. After talking to Diablosport we decided to try their new inTune hand held programmer and see what our favorite tuner, Chris Jenson, could find in the engine tuning.
We did the install on jack stands in the garage. It was easier than we expected, but still a time consuming project, so allow at least a full weekend to do the install yourself. We baselined the car on the dyno at Granatelli Motor Sports in Oxnard, California before the install, and afterwards let Chris tune it and run it on the GMS dyno again. Not to spoil the end of this story, but the results far exceeded our expectations.