BEFORE
You might recognize this GMC Sierra from our '09 Truck of the Year found in issue 2. After we were done testing it in its stock configuration, we started turning wrenches on it to see how good we could make it look and perform, starting with the basics. McGaughy's supplied us with their 2/4 lowering kit to improve the looks and handling. We headed to Traders Sport Trucks in Santa Fe Springs, California, where Ox handled the entire install in just 2 1/2 hours. Don't expect to be able to repeat that in your driveway, Ox has done more than one of these kits.
AFTER
For the new rollers, we clicked onto Discounttiredirect.com to check out their selection. Our Sierra already started its life with 20-inch wheels, and we thought about moving up to 22s, but we didn't want to sacrifice too much in the ride quality department, it also helped to keep the price within our budget. To compromise for the 20-inch wheels, we opted for a little less sidewall in the Nitto NT420S that were shipped from Discounttiredirect.com mounted and balanced (with TPMS sensors) to our Liquid Metal wheels. All we had to do was throw them onto the truck and get an alignment.
We also hooked up with True Flow and MBRP to help the sound and performance of the 5.3L V-8, and those two parts we handled in our own garage. Check out the following pages where we'll give a stock Sierra a bolt-on makeover.
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Other than the leaf springs, here's the McGaughy's lowering kit. The spindles are cast wit
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First, Ox from Traders, in Santa Fe Springs, California, measured the ride height of the S
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The calipers were unbolted and hung from the frame to keep tension off the brake lines. Wi
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Ox marked the brake backing plate where it needed to be cut. He used aviation shears for t
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Side by side with the factory spindle, you can see there's no hole for the top bolt on the
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After a little blue Loctite, Ox threaded the stud in and used an open-end wrench to tighte
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The new spindles were bolted back onto the control arms. A little prying was necessary to
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The factory wheel-speed sensor clamps into a small sheetmetal bracket. Ox was careful when
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To start the rear, Ox unbolted the factory trailer hitch and removed the leaf spring U-bol
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The bolts for the leaf springs go from inboard the truck and point out, which meant that t
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The small lift block on the factory spring was reused on the McGaughy's spring, as well as
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With the obstacles out of his way, Ox unbolted the spring and shackle.
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The McGaughy's shackle is on the bottom. Combined with a slightly flatter spring, they wil
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The new leaf springs were secured with the factory U-bolts and plate.
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The new shackle has plenty of room to cycle through the spring's travel. After the bolts w
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Moving to the performance side, the True Flow XDi intake came with a huge filter and all o
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Here's the factory engine bay. The first order of business was disconnecting the battery's
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Next we unplugged the MAF sensor.
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We used a flathead screwdriver to loosen the hose clamps on the throttle-body and at the M
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Here's the massive XDi intake canister and filter. The air goes in through the center of t
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The XDi canister uses that rubber grommet to stay in place, in addition to being bolted in
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The silicone couplers were loosely fitted until we were sure everything was correct. Once
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We tackled the exhaust in the driveway by our garage. First we unbolted the flange just be
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Side-by-side, the stainless MBRP exhaust looked a whole lot better. Its straight-through m
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After pre-assembling the pieces on the ground, we took the exhaust apart and worked front
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The double-wall polished stainless exhaust tip exits where the factory tip did, but looks
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One last step before the wheels were bolted on: The rear brakes have these copper clips to
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Here's how we got our wheels from DiscountTireDirect.com. They were mounted and balanced a
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Here's the combo after being unwrapped: 20x9-inch Liquid Metal Lithium 6 wheels and 265/50
From The Driver Seat
The tire-bed gap at the rear of the truck was pretty large on the new truck, and the McGaughy's 2/4 drop put an end to that. Ride quality decreased initially, as the rear suspension only had about an inch before the truck was riding on the bumpstops. The factory bumpstops are a dense foam, and are about four inches long, so we trimmed an inch off the bottom to give more room for the suspension to cycle. There's still a large margin of safety, as there's no way the tires are going to rub with three inches of bumpstop left. We could have gone with a much shorter polyurethane bumpstop, and that's still an option in the future. Our chosen wheel and tire package complements the chrome bumper, grille, and emblems better than the factory machined aluminum, and the Nitto NT420S performance tires add some much-appreciated grip. The installed Tire Pressure Monitoring Sensors (TPMS) needed to be synced with the truck through a process of releasing and adding pressure, or you can have your dealer do the same. Our favorite part of the install was the sound of the 5.3L V-8 after the True Flow intake and MBRP exhaust. We drove with just the intake installed for a day and really liked the added rumble that kicked in at about 1,900-rpm under load, and at any rpm under WOT. When the truck was at part throttle, like when maintaining speed on the highway, the truck seemed as quiet as ever. Bolting on the MBRP exhaust only added to the great sounds, but it was noticeable at idle while outside the truck. Inside the truck at cruising speeds, the truck sounded quiet and tame, but mash on the throttle and the intake and exhaust let the V-8 be heard.
YOUR QUESTIONS ANSWERED
Time Spent Working: About 5 hours
(21/2 for the suspension, ½ for the intake, and 11/2 for the exhaust since we did it in our own garage without a lift).
Degree Of Difficulty: Easy
All of the parts bolted on, but a lift was a big help when installing the suspension.
Parts Used:
-Discount Tire Liquid Metal Lithium 6 wheels and 265/50R20 Nitto NT420S tires $1,815.00
-MBRP single side exit cat-back exhaust, part #S5036409 $466.24
(price from autoanything.com)
-McGaughy's 2/4 lowering kit, part #34000 $809.95
(price from summitracing.com)
-True Flow XDi intake #10708 $339.95
(price from autoanything.com)
Total Cost: $3,431.14 (not including tax or labor)