Granatelli Motor Sports LS6 Axle-Back Exhaust - Chevy High Performance Magazine

Granatelli Motor Sports LS6 Axle Back Exhaust Tips

Let's not kid ourselves, there's truly nothing like the sweet rhapsody of eight cylinders as you're rowing through the gears. And when it comes to the C5 Z06, we'll be the first to say that The General did a remarkable job with the factory pipes. Especially when you take into consideration that this was the first production exhaust to feature titanium construction. If you didn't already know, this was part of the Z06's weight reduction program. The tone is bit throatier over the standard C5, but after a bit more seat time, we started craving a system that would kick up the decibel factor slightly, better representing the stout LS6 powerplant.

In deciding on what setup to go with, it came down to several factors. We contemplated a complete exhaust system, beginning with a set of long-tube headers for all out performance; however, reality kicked in and directed us to a package that that would still allow us to pass our stringent California smog emissions. The only viable option was to upgrade to an axle-back system, keeping the factory catalytic converters in place.

As mentioned earlier, we knew we wanted something to tickle our ears, but we certainly wanted to avoid upsetting our neighbors during the occasional early morning commute. Above all, we also wanted to stay clear of any unwarranted drone. If you're not familiar with this, it's when the exhaust frequency is constant at a certain rpm; this can get a tad annoying on long drives and makes it difficult to interact with passengers.

The exhaust system that addressed all of our concerns was Granatelli Motor Sports (GMS) LS6 axle-back exhaust system. This system features a complete T-304 stainless steel construction, a straight-through muffler design for maximum flow, and quickly bolts on with minimal effort. Net gains to the rear wheels were very respectable and showed immediately on the chassis dyno, but you're going to have to read on to see those numbers. When it came to road testing, we took a 600-plus-mile round trip up to NorCal and came back with one simple verdict: we have a winner.

Quick Notes
What We Did
Swapped out the factory exhaust for a Granatelli Motor Sports axle-back system

Bottom Line
Gained performance and a sweet sound

Cost (Approx)
$800

We started by removing the two sway bar mounts with an 18mm socket and 15mm wrench. Some prefer to remove the sway bar completely by disconnecting it from the endlinks, but you can do what we did and simply drop the sway bar down and out of the way.

We started by removing the two sway bar mounts with an 18mm socket and 15mm wrench. Some p
The factory H-pipe extends below the transmission, it's here you'll need to remove four bolts to disconnect the factory axle-back system.

The factory H-pipe extends below the transmission, it's here you'll need to remove four bo
We've heard of people using a Sawzall to remove the factory pipes. Rather than destroy a perfectly good exhaust-with the sway bar already out of the way, it's just a matter of finessing the pipes out in one piece. Bear in mind there are many enthusiasts who are looking to purchase the titanium exhaust, which will allow you to recoup some of your coin back for your new setup. In our case, we saved it to put our Z back to factory trim, should we ever want or need to.

We've heard of people using a Sawzall to remove the factory pipes. Rather than destroy a p

The final pair of bolts that holds the muffler onto the chassis were removed with a 10mm socket.

The final pair of bolts that holds the muffler onto the chassis were removed with a 10mm s
Lastly, we removed the factory rubber hanger and followed the same procedure for the other side.

Lastly, we removed the factory rubber hanger and followed the same procedure for the other
The GMS axle-back exhaust is a complete 2.5-inch mandrel bent system that comes with all the necessary hardware, including fresh gaskets that connect to the factory H-pipe. The sectioned press-fit design allows for unlimited adjustability and splits into dual 2-inch exit primaries that lead into the slash-cut 4-inch tips.

The GMS axle-back exhaust is a complete 2.5-inch mandrel bent system that comes with all t

We started by connecting the main tube into the H-pipe. From there we connected the 90-degree tube and tightened it down with the supplied clamps, which takes a 15mm socket.

We started by connecting the main tube into the H-pipe. From there we connected the 90-deg
The muffler assembly ties into the 90-degree tube, mounting with the same style of clamps used earlier. The pipe exiting the muffler is a 180-degree tube that comes pre-welded from the factory.

The muffler assembly ties into the 90-degree tube, mounting with the same style of clamps
Here you can see Joe Granatelli, the lead man at GMS, attaching the muffler assembly to the factory rubber hanger and mounting it to the chassis; again, using the factory bolts with a 10mm socket.

Here you can see Joe Granatelli, the lead man at GMS, attaching the muffler assembly to th

With the muffler supported and mounted by the hanger, we loosely assembled the tubing with the dual exhaust tips.

With the muffler supported and mounted by the hanger, we loosely assembled the tubing with
Once the system was completely installed, we simply snugged up the bolts and fired up the Z. After reaching normal operating temperatures to allow the exhaust to expand, we were able to make final adjustments to our liking and tightened down the system for good.

Once the system was completely installed, we simply snugged up the bolts and fired up the
There you have it, an exhaust system that's aesthetically pleasing and offers real world performance without warranting ear plugs. All said and done, the GMS system certainly did the job we asked for and the sound is downright sexy!

There you have it, an exhaust system that's aesthetically pleasing and offers real world p