I think most of us will agree a white Chevrolet/GMC pickup going down the freeway isn’t something to get very excited about. The reality is these pickups are a dime a dozen. Knowing that a white pickup truck is almost invisible, we decided we wanted to add a little more sex appeal to our GMC Sierra. We started by adding an emissions-legal ProCharger, which bumped up the truck’s power from 260 horsepower and 281 lb-ft to a healthier 419 horsepower and 422 lb-ft of torque. And while we’re happy with the newfound gains, we can’t help but think the factory exhaust system could be a hindrance. So our next step was to find a great-sounding exhaust in hopes to free up a few more ponies. However, we wanted to update the exhaust so that it would remain smog-legal in California.
Navigating the desire to modify a vehicle while satisfying smog-legal requirements can be a tricky tightrope to walk on, especially in California. However, it can be done. While searching for a good exhaust system to upgrade our Sierra, we were cautious about locating a system that had a California Air Resources Board (CARB) 50-state legal exemption. This exemption would ensure our truck would pass smog after we improved its performance. Finally, we found exactly what we were looking for at JBA Performance Exhaust. JBA had both a set of shorty headers with a CARB exemption and an exhaust system that would give us the sound and performance we were looking for.
We started our adventure in the shop with the JBA shorty headers. The passenger side was simple. We unbolted the stock exhaust manifold from the exhaust Y-pipe (three bolts on the flange) and then unbolted the manifold from the head. The JBA piece went in like butter, and we used their graphite gaskets to keep away any pesky exhaust leaks. After we cinched down some bolts, we were done on the right side of the truck.
On the driver’s side, things weren’t as easy. We had to unbolt the steering shaft to help with access. It was clear the installation on the driver’s side would take a bit longer than the header on the passenger side. And since our GMC Sierra already had a supercharger mounted on the driver’s side, access was a bit tight but didn’t make things impossible. Don Lindfors, Director of Exhaust R&D, PerTronix, Inc., said, “It doesn’t surprise me your installation was easy. We design JBA headers and manufacture them with the correct tolerances, so they fit perfectly.”
We removed the intake tube and plug wires to make extra installation room on the driver side. We were a bit impatient ripping off the plug wires, and after 60,000 miles, the old OEM plug wires fell apart in our hands. No problem. We ordered a set of new PerTronix plug wires and slapped those babies on once both headers were completely installed.
Once the JBA shorty headers were on tight and our new PerTronix/JBA plug wires were snug, we moved on to the rear portion of the exhaust. Since the stock exhaust was just too quiet for our taste, we opted for JBA’s Performance Exhaust system (PN 40-3051), which would replace the exhaust south of the catalytic converter. Again, leaving the stock catalytic converter alone and in the stock location is the key to gaining CARB compliance.
The first step in installing a new exhaust system is getting a vehicle up in the air and getting dirty pulling off the old exhaust system. We cut the exhaust with a reciprocating saw to help remove the pipes around the rear axle. The stock system comes with a resonator and a muffler with a fairly restrictive valve. The JBA exhaust comes with a single muffler with two internal perforated tubes for a more free-flowing exhaust.
The original JBA kit came with a single-tip. We upgraded to a brand new design which has two tips at the exit. Because Chevrolet/GMC 1500 trucks come with different bed lengths and manufacturing tolerances, one pipe from the JBA kit needed to be test fit and cut to size to fit our application. Once we had the length right, we started clamping the system together and connecting it to the stock Y-pipe utilizing the provided clamps. The clamps were good quality (not something you always get with an aftermarket exhaust system) and worked well holding the system together.
Installing an exhaust system takes a little finesse and patience to get the pipes in the correct location, so the exit tips are at the right angle. Getting the exhaust tightened and centered in the chassis is crucial, so you don’t get those annoying exhaust rattle noises. The JBA exhaust hangers’ location was in the exact location to hang the system under the pickup on the OEM mounts.
With a lift and the right tools, we installed all JBA components, shorty headers, new plug wires, and rear exhaust in less than five hours. When we fired up the GMC we were pleasantly surprised the exhaust was noticeably louder at cold start. Overall, the exhaust is more audible at idle and at wide-open throttle. The good news was the exhaust did not drone or cause noise at partial throttle, a common complaint of many aftermarket exhaust systems. We liked what we heard from the JBA setup. The next step was to put it on the dyno and determine how much more power we gained.
Since this is a California truck, it’s relegated to 91 octane and CARB-legal parts. While a trip across the country toward the east quickly lands us into the Promised Land of 93 octane at gas stations, this plan is not practical. The only way to get higher octane in California is by using an octane additive in the tank. Fortunately, VP Racing Fuels makes Octanium Unleaded Octane Booster.
VP’s Octanium Unleaded Octane Booster has been proven to boost octane up to seven numbers, meaning 91 octane mixed with Octanium would be 98 octane. And since VP Racing Fuel’s unleaded formula is designed for unleaded engines, it won’t harm catalytic converters or oxygen sensors. Travis Laveault, senior marketing manager of VP Racing Fuel said, “Not only does higher octane increase power, but Octanium eliminates knocking and pinging, cleans fuel injectors, and knocks out gum and varnish build-up. Overall, it improves throttle response and acceleration.”
With all of our bolts tightened down from our project, it was time to strap down the Sierra onto our chassis dyno and see if our hard work would pay off in the horsepower department. The truck sounded great at wide-open throttle with the JBA exhaust. We didn’t hear any pinging in the engine, thanks to the VP Racing Fuel Octanium. We did each of our pulls in third gear. What we found was that our horsepower went up from a 419 horsepower baseline to 431 horsepower. Of course, there is nothing wrong with having 431 horsepower.
Not all shop projects go as planned, and not all pre-planned modifications create horsepower, but ours did. As a result, our shop project was a win-win. The job was easy, completed in less than five hours, and we got a great sounding track with more horsepower.