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2003 Chevy Silverado- Project Over/Under: Part Two- Bolt on Power

We Freshen Up a 4.8L LS1 With K&N, Jet, Hypertech & JBA

May 16, 2018
Photographers: Jeremy Cook
Typically, when you read magazine stories about installing aftermarket performance parts on LS engines, the main goal is to extract every available horsepower number out of the engine. If the owner of the truck isn’t happy with the results, you may read about a whole other set of go-fast parts being installed the next month. Don’t get us wrong, we like horsepower as much as the next guy, but sometimes on these tried-and-true platforms—like the 100,000-mile 4.8L engine in our case—all the experiments have already been done. The guesswork has been taken out of the equation, and unless you want to spend thousands of dollars and unlimited time swapping different brands of parts for just a few more elusive ponies, you can trust the experts and find a bolt-on combination of parts that makes all the power you’re going to find without forced induction or a complete engine rebuild.
Our bolt-on bonanza started with a call to Jim Hairston, longtime drag racer and owner of both JBA Performance Exhaust and Pertronix. Between the two companies, we sourced the Shorty headers, cat-back exhaust, Flame Thrower coils, and 8mm plug wires. With the spark and exiting air covered, we moved to the incoming air and contacted K&N for an FIPK air intake and JET Performance for its Powr-Flo throttle body and mass airflow sensor. Finally, we wanted a reliable off-the-shelf tune for the truck, so we contacted Hypertech for a Max Energy power programmer.
Our old friend Thomas Stevens recently opened Powerhouse Performance in Simi Valley, California, and has already made a name for himself doing everything from diesel performance upgrades to full chassis-up classic truck builds, so we knew our engine upgrades would be a no-brainer for Thomas and his talented crew. They also helped us out by going the extra mile and replacing our thermostat, oil pressure sensor, and oil and fuel filters while we were there.
After a hard day’s work, we were back on the road in what seemed like a totally different truck. The increase in power and throttle response was truly impressive. We really think we found the sweet spot between the money spent and the added power and driveability. We will no doubt log many miles in our Silverado with this setup.
Photo 2/36   |   Before: Here’s our well-worn 4.8L, virtually untouched by human hands as far as we can tell (save for oil changes).
Photo 3/36   |   After: We breathed new life into the old LS, and it in turn breathes a whole lot better.
Photo 4/36   |   The full Monty of bolt-on performance parts begins with the JBA 50-state-legal Shorty headers (PN1850S-2JT). They’re made with 1 5/8-inch stainless tubing and are titanium-ceramic coated.
Photo 5/36   |   JBA also supplied its stainless 3-inch single-side-swept cat-back exhaust kit (PN 40-3009). JBA has tested these trucks with the headers and exhaust, and they’re good for an easy 10hp bump.
Photo 6/36   |   Next on our parts list were a couple of items from JBA’s sister company, Pertronix. We ordered up a set of its Flame Thrower LS truck coils (PN30848) and a set of black 8mm LS plug wires.
Photo 7/36   |   Our next stop was JET Performance Products, for its Powr-Flo Performance throttle body (PN76100) with a modified air inlet to improve airflow and throttle response, and the JET Powr-Flo mass air sensor (PN69101) that delivers improved horsepower, torque, and mileage by simply replacing the restrictive stock mass air sensor.
Photo 8/36   |   To complete the new air system, we turned to the tried-and-true K&N 57 Series FIPK performance air intake system (PN57-3021-1), which is good for 9 hp on these 4.8L engines.
Photo 9/36   |   The icing on the cake would be the Hypertech Max Energy Power Programmer (PN32500), which adds maximum power and performance to our 4.8L with a few touches of the buttons! On this application, it is good for another 9 hp.
Photo 10/36   |   We arrived at Powerhouse Performance in Simi Valley, California, bright and early and knocked out the install in one day. We put the truck on the lift and knocked all we could from underneath the truck. We began by cutting the stock exhaust in half so it could be removed easily.
Photo 11/36   |   The muffler and tailpipe were slipped off the hangers and removed from the truck. The front section was also unbolted from the Y pipe.
Photo 12/36   |   We unbolted the Y pipe from the stock exhaust manifolds. We also drained the oil and installed a new K&N oil filter while we were in the neighborhood.
Photo 13/36   |   Next, we wrestled out the exhaust manifolds from either side of the LS block. Then we proceeded to remove the stock spark plugs and clean up the area.
Photo 14/36   |   The JBA headers come complete with gaskets and bolts and are a perfect fit, so the installation is as easy as header installs get.
Photo 15/36   |   We torqued the bolts to about 25 ft-lb from inside to outside and even remembered to reconnect the oil dipstick tube. We also installed some new AC Delco plugs while we were there.
Photo 16/36   |   On the valve covers, we disconnected the wiring harness and unbolted the coil brackets. We also pulled the valve covers, gave them a solvent bath, and reinstalled them with fresh gaskets.
Photo 17/36   |   On the bench, we disconnected and unbolted each coil, cleaned up the brackets and harness, and bolted up the new Pertronix truck-style coils.
Photo 18/36   |   The new and cleaned-up assembly was then returned to the valve cover. Here it is hooked back up.
Photo 19/36   |   We then finished up the area by installing the 8mm Pertronix plug wires, which are purpose-built for use with the JBA headers.
Photo 20/36   |   With the truck back in the air, we bolted both sides of the Y pipe up to the new headers using the new hardware. We also reinstalled the O2 sensor we removed to get a straight shot at one of the bolts.
Photo 21/36   |   The JBA exhaust install started by bolting up the first section to the Y pipe.
Photo 22/36   |   Next, we loosely installed the stainless muffler in place between the two pipe sections.
Photo 23/36   |   Thomas slid the tailpipe into place, making sure it cleared the spare tire and was snug up to the bed.
Photo 24/36   |   We went back through and did some fine tuning before the final tightening of all the joints. It’s not shown, but we also replaced the stock fuel filter with a K&N unit before putting the truck back on the ground.
Photo 25/36   |   Back up on top of the engine, we ditched the factory air intake and the stock mass air flow sensor.
Photo 26/36   |   Then, we removed the stock throttle body. The gasket goes, too, as the new JET Powr-Flo unit comes complete with a fresh one.
Photo 27/36   |   The JET throttle body bolts right up like stock. It’s hard to see, but there are coolant lines on the bottom that were removed and replaced.
Photo 28/36   |   K&N’s FIPK air intake kit was next. The first step was to bolt the JET Powr-Flo mass air sensor to the airbox using the provided bolts.
Photo 29/36   |   Then the rubber gasket was fit onto the airbox.
Photo 30/36   |   We bolted up the bracket assemblies using the rubber isolators and attached them in the factory spots.
Photo 31/36   |   The silicone couplers were loosely attached to the intake tube, which was in turn slid into place on the JET throttle body and MAF sensor.
Photo 32/36   |   After some final fitting, all four of the hose clamps were tightened down.
Photo 33/36   |   Finally, the pre-oiled K&N air filter was clamped into place in the airbox.
Photo 34/36   |   Other than the air intake kit and the fact that the engine compartment is super clean, it’s hard to see all the work that has just taken place out at Powerhouse Performance.
Photo 35/36   |   But upon closer inspection, the Flame Thrower coils and plug wires, along with the JBA headers, are a dead giveaway.
Photo 36/36   |   The last step was to hop in the cab and plug in our Hypertech Max Energy power programmer. All you have to do is follow the prompts, answering yes or no and making a few adjustments for premium fuel, shift points, and such, and the tuner does the rest. Soon, we were back on the road with a totally renewed 4.8L LS. The sound is awesome, and the throttle response is 100 percent better. With a day’s work, we added in the neighborhood of 30 to 40 hp!


Bartlett, TN 38133
K&N Engineering
Riverside, CA 92507
PerTronix Performance Products
San Dimas, CA 91773
JBA Performance Exhaust
Powerhouse Performance
JET Performance



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