"This truck has a big ol' nasty ZZ4 motor with rear tires that are a foot and a half wide. But the sound it makes doesn't match all the commotion." Harold Davis of Costa Mesa, California, is like a lot of Custom Classic Trucks' readers: he loves all kinds of trucks. By day, Harold drives a conventional Peterbuilt pulling doubles, but when his shift ends it's over to his private workshop hidden away in a SoCal industrial park where he can work on his pickups without being bothered. Harold is a pretty low-key kind of guy. Sure, he's had his fun traveling over 100 mph, a quarter-mile at a time-but those days spent at the dragstrip are behind him now. These days for relaxation and enjoyment Harold likes to cruise his '55 Chevy pickup down to the donut shop on Saturday, or to a local car show. Running with open headers on the street is not an option for Harold. He just likes to roll low and slow. Of course, all bets are off when Harold's destination is one of the many local events in southern California that feature open-header cruising. Hey, can you blame him? After all, who wants to be the meek, quiet guy when the badasses are out to play? To enjoy the benefits of both worlds-the throaty mellow sound of Flowmaster mufflers, and the roar of Hooker Headers-Harold took his '55 over to the Muffler Man in Placentia, California, where Josh custom-installed a pair of Flowmaster mufflers behind Harold's existing set of Hookers. In between the Hookers and the Flowmasters, Josh custom-fabricated a pair of 21/2-inch pipes and then plugged in a pair of QTP Electric Cutouts. With a background in drag racing, Harold knew installing a pair of cutouts often meant more cool noise, but with a distinct possibility of losing bottom-end torque and horsepower. Before making the final decision to go with the QTP Electric Cutouts, Harold did a little research and learned that the folks at QTP claimed their setup would actually add torque and horsepower. When Harold told us what he'd heard about the QTP Electric Cutouts, we expressed our doubts and suggested that after Josh the Muffler Man had worked his custom-exhaust fabricating magic we run a dyno test and find out. As soon as Josh fired up the '55 with its new, bitchin'-sounding Flowmasters, we jumped in the '55 and drove it to our tech center. Within a few minutes, Jason Scudellari had Harold's ZZ4-powered Chevy pickup on our Mustang chassis dyno making a series of pulls. The first pulls were all made with the QTPs corked up. After ensuring all of the test conditions were identical to the first pulls, Jason blasted the '55 back up to 5,300 rpm and ran her with the QTPs open. Although our results weren't as impressive as some of QTP's other applications, we have to admit we were impressed that the ZZ4-powered '55 really did make more horsepower and torque. After averaging our results, the closed numbers were 244 hp and 269 lb-ft of torque-and then 249 hp and 277 lb-ft of torque with the QTPs wide open. As the saying goes: When it comes to money and horsepower, every little bit helps. Now Harold has a thundering exhaust note to match his truck's badass profile.