The Chevy Corvette Z06 is an impressive car right out of the box. It sounds awesome, with gobs of power to match. The stock Z's performance capabilities are quite high, but it's in a car guy's blood to make a fast car even faster-or louder, in this case. The owner of this Z06 initially installed a set of headers and a cat-less exhaust with an X crossover pipe, but he retained the stock mufflers. After driving the car in that configuration for a few hundred miles, he decided to further improve its sound quality and reap the benefits of a couple extra horses, too.
Rather than ditch the stock equipment in favor of a pair of aftermarket mufflers, he took the car to In Tune Motorsports, in Charleston, Tennessee, to receive what's commonly referred to as a muffler mod. In Tune's Keith Kile performed the modification, the second job of this sort he's performed in the past few months.
The first step is to remove the original mufflers, so the job begins with unclamping the exhaust system and prying them from their hangers. Then it's a matter of cutting the mufflers to access the baffled pipe that's in use when the vacuum-operated valve opens to allow for straight-through airflow. The drilled pipe is then capped with a solid piece, and the muffler is welded together again.
The first step is to unclamp...
The first step is to unclamp the exhaust system and remove the mufflers. Keith Kile knows his way around a C6 Z06 and has the exhaust off in a matter of minutes.
The result is very nice, because at idle and during regular driving, the car sounds totally stock. But when you get on the throttle hard, it's a whole different animal. This modification is sometimes called the "poor man's Borla," because you can do it on your own and spend just a few bucks on cut-off wheels and grinding discs. Although the owner of this car chose to have In Tune Motorsports handle the work, he still ended up spending a fraction of the cost of an aftermarket exhaust system. The guys at In Tune say that while there's not much of a horsepower gain, the difference in sound is undeniable. Follow along now as we detail the steps of the modification.
With the mufflers off the...
With the mufflers off the car, we can take a look at the Z06's exhaust-control actuator. When the vacuum reaches a certain level (based on throttle input), a butterfly opens in the tailpipe, allowing air to flow through a more straight-through path.
To access the muffler's internals,...
To access the muffler's internals, Kile uses a cut-off wheel and cuts out a rectangular panel, just inside the factory spot welds. Before he starts cutting, he uses a Sharpie to mark the desired cuts.
With the panel removed, Kile...
With the panel removed, Kile grabs the insulation and pulls it out of the muffler. There's quite a bit of packing inside the muffler, but Kile removes it all. He'll repack it when the job is complete.