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C6 ZR1 Exhaust System - Pipes In The Fast Lane
Corsa's RSC Track Exhaust System Unleashes More Sound And Fury From A New ZR1
Christopher R. Phillip
Dec 6, 2010
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C6 ZR1 Exhaust System - Pipes In The Fast Lane
The Corvette ZR1 looks and performs on par with the world's finest exotics, but did Chevrolet limit its output by fitting it with a restrictive exhaust system? To find out, we're going to introduce the factory cans to the nearest dumpster and replace them with the Corsa RSC Track Exhaust System.
Our first step is to strap the ZR1 onto Backstreet Performance's mobile Dynojet dynamometer and ask company co-owners Rich and Erik Johnson to put it through three successive, no-holds-barred pulls. The best yields readings of 517.01 hp and 500.36 lb-ft of torque.
Take a good look at the ZR1's stock exhaust tips and mufflers before we retire them for good. We'll show you a photo of the new Corsa tips and mufflers installed later in the story and let you decide which is the better-looking system.
Now it's time to extract the factory after-cat system. Corsa Lead R&D Technician Mark Bockwich uses a 15mm socket to loosen both of the factory crossover-pipe clamps from the axle pipes (one on each side of the transmission).
Staying with the 15mm socket, Bockwich removes the two bolts and nuts connecting the factory crossover pipe to the converter pipes. (On the ZR1 or Z06, the lower two fasteners are bolts, and the upper two are nuts. On a standard C6, all four fasteners are nuts.)
The crossover-pipe assembly is attached to the factory spring hangers by two nuts. He removes them with a 13mm socket, freeing the crossover-pipe assembly from its remaining mounting points underneath the Corvette.
The factory crossover pipe assembly is a slip-on type, allowing Bockwich to easily slide it away from the converter pipes. This is necessary to allow the factory mufflers to be removed from the vehicle.
Bockwich cuts the factory over-axle pipe (passenger side only), giving it more exit clearance and making its removal quick, easy, and safe. This step is critical to the procedure because it minimizes the chance of damaging the fuel and vapor-return lines, as well as the myriad wiring that runs along the underbody. Corsa suggests using a chain-style cutter for slicing through the pipe, as shown.
Bockwich sprays the factory mufflers' rubber isolators with soapy water (for lubricity), then removes the hangers.
He then removes the rear sway bar from its rear mounting brackets using an 18mm socket on the lower nuts and upper bolts, along with a 15mm wrench to hold the lower bolt heads stationary to prevent bolt-spinning (not shown.) Next, he swings the bar out of the way, creating the clearance necessary for the factory mufflers/over-axle pipe assembly to slide out.
The ZR1's factory dual-mode exhaust is vacuum-activated. Bockwich removes both vacuum lines (one on each side) from their butterfly-valve assemblies.
With its over-axle pipe trimmed, the passenger-side muffler assembly slides out freely.
Removing the driver-side muffler assembly requires extra care. Bockwich applies slight pressure to the transmission line so the factory over-axle pipe can slip by unobstructed.
With the stock exhaust fully removed, the ZR1 is ready for the Corsa RSC Track Exhaust System.
Before we get started on the upgrade, let's compare the new preassembled Corsa system (on the left) to the ZR1's factory exhaust. It's easy to see that the Corsa set-with its 321 military-grade stainless steel construction-has better looks and, presumably, longer durability. In fact, it comes with a limited lifetime warranty.
A close-up view of the factory 3-inch axle pipe reveals that it necks down to 2.5 inches as it enters the muffler. The factory tips are also a 2.5-inch internal design.
The Corsa RSC Track Exhaust System (shown unassembled) features a fully-3-inch, straight-path design for the over-axle pipes and muffler inlets/outlets. The tips measure an even larger 4 inches.
Before installing the Corsa system, Bockwich reinstalls the factory crossover-pipe assembly, repeating its removal instructions in reverse order.
He then reinstalls the factory crossover-pipe spring hangers, again by repeating its removal procedure in reverse.
Starting on the passenger side, he loops the Corsa axle pipe over the axle...
...and slides the new pipe's inlet into the factory crossover-pipe outlet.
He tightens the pipe into place using the tack-welded factory clamp on the crossover pipe. Note: Bockwich tightens the axle pipe into the clamp so that it is not quite snug. He'll leave it that way and lock in final positioning adjustments later.
He then routes the driver-side Corsa axle pipe over the ZR1's rear axle and slips it into the factory crossover pipe (not shown).
Next, he tightens the Corsa axle pipe to the stock crossover pipe, via the factory-supplied clamp.
Remember the factory vacuum-activated dual-mode exhaust feature? Bockwich installs the supplied vacuum caps to seal off the factory vacuum line. (Additional instructions that come with the Corsa system show how to easily disable the factory dual-mode exhaust's electronics by removing a fuse.)
After sliding the Corsa muffler hangers into the factory rubber isolators, Bockwich slips the passenger-side muffler inlet over the Corsa axle pipe and attaches it loosely to the pipe with a supplied clamp using a 15mm socket (not shown). He repeats the process for the driver side.
Bockwich adjusts the Corsa system for tip rotation and exit length, then "snugs up" the mufflers to the axle pipe. (Note: Corsa recommends that you pay close attention to clearances around the rearend, transmission lines, and frame above the axles.)
He reinstalls the sway bar, loosely at first using sockets...
...and then uses a torque wrench to tighten the fasteners to 50 ft-lb (top) and 70 ft-lb (bottom).
Finally, he makes adjustments so that the muffler tips are in perfect symmetry to each other and the ZR1's rear fascia.
Here's how the tips look after installation. Notice how both the left and right sets of tips are equal distance from the top of the rear-fascia cutout.
With the Corsa system installed, it's down off the lift and back up on the Dynojet for three more pedal-to-the-metal pulls.
Incredibly, the car registers max peak-to-peak increases of 19.11 hp and 12.49 lb-ft of torque, making this one upgrade that more than lives up to its billing.
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