LS7 exhaust system on an LS2 = 30 hp
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LS7 exhaust system on an LS2 = 30 hp 
Over the Christmas holiday I installed a 2007 C6 Z06 exhaust system (manifolds, Cats, H pipe) plus Corsa Z06 3 inch Sports on my 2006 C6 A6. I did a pre and post dyno run on a Dynojet 248 for comparasion. The car was tuned (A/R ratio, timing, etc) to the same level for each dyno pull. Pre Z06 exhasut was 343 rwhp and post was 373 rwhp. There are a bunch of Z06 guys putting headers on the Vettes. The shop I use had 4 pairs just collecting dust. However, the Z06 guys tend to keep their NPP mufflers, but Corsa, B&B and Borla all make 3 inch Z06 mufflers. The installation was not difficult. I bought GM LS7 manifold gaskets and some O2 sensor wire extensions for the forward O2 sensors. The clearance around the A6 transmission is tighter than I want, so I will get some minor exhaust pipe work. Manual transmission C6's should be no problem at all. Bottom line. I think this is a good 30 hp mod for C6 Vettes if you can get your hands on a discarded Z06 exhaust system
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The Corsa C6 Z06 cat back is around 1700. The B&B Z06 systems are a bit cheaper at 1400. Borla also makes a Z06 system for around 1700. I think the steep prices are due to the "Corvette" tax. I selected the Corsa Sport system because it has the sound tone I was looking for. It has a nice idle, no drone when cruising on the highway, but it wakes up when you hammer the throttle.
Gotta love the Corsa. It has a nice rumble to it and a slight roar driving around town, but when you hit it, it'll wake up anything.
I wonder how LS7 Manifolds/cats/etc would fit on a C5...
I wonder how LS7 Manifolds/cats/etc would fit on a C5...
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The high price you have to pay for the "good sound" is outragious when you consider that none of the aftermarket catbacks will out flow the stock Z06 exhaust..Vengeance Racing has tested a bunch of them against the stock system and none were better flowing .. welcome to the world of the "Corvette tax" on Vette parts..
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Verdad Gallardo Yeah there's even a noticeable difference in Corvette tax from C5 to C6. My Corsa I bought used off a wrecked C5 for like $450. It has low miles and a couple dents in it... big deal. I saved a ton of cash.
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A C5 conversion might be interesting. The manifolds would bolt to the heads for sure. The portion that bolts to the bottom of the manifold and contains the cat and O2 bungs would probably fit because the C5 and C6 a very similar in that area. Even the tunnel looks similar for the H pipe. The hangars for the H pipe is different. There is no hangar at the front, only one in the rear. If the manifolds and cats would bolt up a good muffler shop to make a H or X pipe.
I know finding some LS7 manifolds isn't hard. I just need to find some cats and the rest shouldn't be too bad. Does that same shop have another pair of manifolds/cats collecting dust?
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I don't think they have any at this point. When the Z06 guys put headers on, they get rid of the manifolds and the portion that bolts to the bottom of the manifold which contain the cats. There is no way they can put on a set of headers and keep the stock cat portion. Usually the headers come with new high flow cats section and the X pipe. So if you can find some used LS7 manifolds and portion that bolts up to it should be there as well.
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I had thought about hooking up the 3 inch Z06 H pipe to my stock 2 1/2 inch mufflers, but did not feel like messing with the exhasut work. I would think that the Corsa 3 inch over the 2 1/2 inch stock mufflers might be worth 10hp? I think Chevrolet claims 6 hp for their new NPP system on the 2008 LS3 Vettes. The system operates like the Z06 mufflers, but others than the vacuum operated valve, I don't know what the exhaust pipe diameter is for the LS3?
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The gain at 3000 rpm was about 20 hp. The gains were better than expected. The Z06 guys pick up very little on their stock LS7 engines with headers only. When they add a cam the header gains are a little more. The tuner ran the testing in 3rd gear, which is close to 1 to 1 in the A6. I don't think the converter was locked for either the pre or post evaluations.
. The Z06 guys pick up very little on their stock LS7 engines with headers only. When they add a cam the header gains are a little more. The tuner ran the testing in 3rd gear, which is close to 1 to 1 in the A6. I don't think the converter was locked for either the pre or post evaluations. Thread Starter
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Attached is the before and after dyno sheets. One has a CF SAE smoothing factor of 3 (338 rwhp and 365 rwhp) and the other is 5. (373 rwhp) I have been told the smoothing factor of 3 is more accurate.
Did the same thing on my 05 in September, only I re-used the BB Route 66 system that I had on it. Modified the H-pipe by cutting the Z06 unit in half and welding the stock C6 end section on it to match up with the mufflers.
Went from 347 to 372 HP; 346 torque to 362.
Rev's much quicker and sounds "throater"
H-Pipe:
Went from 347 to 372 HP; 346 torque to 362.
Rev's much quicker and sounds "throater"
H-Pipe: