powerlabs
10-05-2009, 06:49 PM
I bought my car with 9000 miles and it was stock, aside for the GHL exhaust. I always liked the system; I've driven and ridden in stock C6s before and they are WAY too quiet: I like to know the car I am driving has an engine in it and the stock exhaust has zero character or sound.
The GHL, on the other hand, idles quietly but with a distinct rumble, and wakes up into just the right amount of sound when I'm on the gas.
Adding headers (Kooks 1 3/4 with a catted X-pipe) to the system did not change the exhaust sound in any way (or affected drone in any way) below about 3000RPMs, but after 3K it gave the car a wail that could only be described as exotic. I absolutely loved it.
HOWEVER, as with most (all?) Corvette exhausts, there was drone. Drone is the ressonance you hear at a certain RPM wen the timing between the exhaust pulses matches up with the time it takes for them to travel to the back of the mufflers. I have always been told that GHLs have mininal or no drone, but between 1500 and 1700RPMs it is DEFINITELY there.
I drove the car from Florida to Los Angeles.
Then I drove it from Los Angles to New Jersey
And now I am daily driving it about 70 miles a day. The drone, which happens exactly at the speed traffic flows on the highway, was starting to really get to me! It didn't bother me before but with the amount of driving I have been doing it was driving me insane. Also, everyone who rode with me for long enoug would eventually complain.
It was time to do something.
I had gathered from feedback on the forum that the Corsa Sport exhaust was supposed to have the least drone of all. Some even said it had no drone. It was time to give it a try:
Almost ready to begin. I have my Craftsman wrench set in the trunk and I haven't fetched the car jack yet:
http://www.powerlabs.org/images/c6/ghl.JPG
And here are the two side by side. The Corsas are upside down and the pipes on the GHL aren't staight, but you get the idea. Notice how much larger the GHL tips are, and also the fact that both sides are united and install together. Also notice how much bigger the mufflers on the Corsas are:
http://www.powerlabs.org/images/c6/ghl1.JPG
I didn't get a picture after the job was done because it was already dark once I was done.
Now, my observations:
First and foremost, those Corsas are HEAVY! Their massive mufflers weight over 22lbs more than the GHLs they replaced. Granted the weight is down low and in the back so it won't affect the CG or the balance of the car much, but still, 22lbs is just two pounds less than what you save by ditching the run flats and going to light non run flat tires like the PS2s. If you autocross, it is significant!
Here are the measured weights as per my bathroom scale (there may be up to 2lbs error here):
Corsas: 56.8lbs
GHL: 34lbs
Z06 W/Actuators: 52lbs
They were a pain to install on jackstands too; I barely had enough clearance and I ended up scratching the bottom of the tips slightly because they had to rub up against the ground before I could wedge them in there.
I do like the smaller tips though. It looks more refined, to me.
NOW... The million dollar question: Is the drone gone?
In short... NO! Here is the breakdown:
The Corsa Sport idles louder than the GHLs. The idle is very noticeable inside the car now.
They still drone at 1500 to 1700RPMs.
They pop and crackle on deceleration as much if not more (it seems like more) than the GHLs. I do like that though; this isn't a complain.
They sound different. A little more metallic; not raspy, but rather a more exotic sound, more ferrari-ish if I dare say... Not the low bassy tone you'd expect from a muscle car. The GHLs already didn't have much bass but the Corsas have even less.
The veredict? I really like the way Corsas look (better than the GHL) and I like the way they sound. The idle could be a tad quieter but everything else is perfect. I THINK they drone less... The 22lbs weight increase is too significant for a minor increase in muffling performance though.
I ended up going with C6 Z06 mufflers. Here is the write up on that: http://www.smokinvette.com/corvetteforum/showthread.php?p=304848#post304848
The GHL, on the other hand, idles quietly but with a distinct rumble, and wakes up into just the right amount of sound when I'm on the gas.
Adding headers (Kooks 1 3/4 with a catted X-pipe) to the system did not change the exhaust sound in any way (or affected drone in any way) below about 3000RPMs, but after 3K it gave the car a wail that could only be described as exotic. I absolutely loved it.
HOWEVER, as with most (all?) Corvette exhausts, there was drone. Drone is the ressonance you hear at a certain RPM wen the timing between the exhaust pulses matches up with the time it takes for them to travel to the back of the mufflers. I have always been told that GHLs have mininal or no drone, but between 1500 and 1700RPMs it is DEFINITELY there.
I drove the car from Florida to Los Angeles.
Then I drove it from Los Angles to New Jersey
And now I am daily driving it about 70 miles a day. The drone, which happens exactly at the speed traffic flows on the highway, was starting to really get to me! It didn't bother me before but with the amount of driving I have been doing it was driving me insane. Also, everyone who rode with me for long enoug would eventually complain.
It was time to do something.
I had gathered from feedback on the forum that the Corsa Sport exhaust was supposed to have the least drone of all. Some even said it had no drone. It was time to give it a try:
Almost ready to begin. I have my Craftsman wrench set in the trunk and I haven't fetched the car jack yet:
http://www.powerlabs.org/images/c6/ghl.JPG
And here are the two side by side. The Corsas are upside down and the pipes on the GHL aren't staight, but you get the idea. Notice how much larger the GHL tips are, and also the fact that both sides are united and install together. Also notice how much bigger the mufflers on the Corsas are:
http://www.powerlabs.org/images/c6/ghl1.JPG
I didn't get a picture after the job was done because it was already dark once I was done.
Now, my observations:
First and foremost, those Corsas are HEAVY! Their massive mufflers weight over 22lbs more than the GHLs they replaced. Granted the weight is down low and in the back so it won't affect the CG or the balance of the car much, but still, 22lbs is just two pounds less than what you save by ditching the run flats and going to light non run flat tires like the PS2s. If you autocross, it is significant!
Here are the measured weights as per my bathroom scale (there may be up to 2lbs error here):
Corsas: 56.8lbs
GHL: 34lbs
Z06 W/Actuators: 52lbs
They were a pain to install on jackstands too; I barely had enough clearance and I ended up scratching the bottom of the tips slightly because they had to rub up against the ground before I could wedge them in there.
I do like the smaller tips though. It looks more refined, to me.
NOW... The million dollar question: Is the drone gone?
In short... NO! Here is the breakdown:
The Corsa Sport idles louder than the GHLs. The idle is very noticeable inside the car now.
They still drone at 1500 to 1700RPMs.
They pop and crackle on deceleration as much if not more (it seems like more) than the GHLs. I do like that though; this isn't a complain.
They sound different. A little more metallic; not raspy, but rather a more exotic sound, more ferrari-ish if I dare say... Not the low bassy tone you'd expect from a muscle car. The GHLs already didn't have much bass but the Corsas have even less.
The veredict? I really like the way Corsas look (better than the GHL) and I like the way they sound. The idle could be a tad quieter but everything else is perfect. I THINK they drone less... The 22lbs weight increase is too significant for a minor increase in muffling performance though.
I ended up going with C6 Z06 mufflers. Here is the write up on that: http://www.smokinvette.com/corvetteforum/showthread.php?p=304848#post304848