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Discussion Starter #1
My apologies if someone has a solution for this but I have been searching for days on the internet and this forum and couldn't find anything that resembles my problem.

Last September I bought my Solstice - 2006 5spd with only 32k on it. Loved driving it for the month before I stored it for winter. During the winter, i began to do some mods to it - replaced air intake with AEM CAI, ordered the Solo header, the Solo HF Cat, and the SQR-2 kit. I installed the CAI myself as it isn't tough to do, but had the header, cat, and SQR-2 professionally installed as I don't have the resources to do it myself. I also purchased the Vector VMS tune/cable.

Needless to say it was really loud, too loud for my liking, and after reading many posts on here, i decided to revert the cat back to the OEM cat. This still did not fix the problem. The exhaust was still very loud and obnoxious. To define loud and obnoxious, the car would have a nice initial exhaust note for the first 5 minutes, then it would change, it would become much louder and anytime you would let your foot of the gas and coast, you would get the exhaust gurgle, followed by a resonance that would increase in its loudness unless you stepped on the gas. However, once you stepped on the gas, the pleasant exhaust note was gone and was replaced with this low end coffee can like sound. (i should mention that driving around 3k did result in the low end loudness diminishing and hearing more of an exhaust note).

So i talked to Jeff at Solo and explained all of this, (he has been very helpful from day one, but I hate to keep bugging them with what if's) and his thought was to remove the Solo Header and check to make sure that the exhaust was not grounding out anywhere. So I had the dealership remove the header, then I replaced the CAI back to stock, and reflashed the ECU back to stock so everything was stock with the exception of the SQR-2.

The problem remained. Still loud, not any quieter, unpleasant to listen to in that range of 2k to 2.8k, resonating when coasting, etc. Contacted Jeff again and his thought was to send out a brand new system to test and have me ship the old one back. brought the new system over to my friends heavy truck repair shop and installed it. While installing it, I noticed that the dealership removed the bottom bracket that supported the cat and apparently threw it out. So I ordered a replacement bracket. While waiting for the new bracket to arrive I drove with the new exhaust and at first it sounded much better. Was quieter, didn't hear any resonance, sounded like it should. That lasted about for about 100 miles, then it was right back to the same old same old. Had the cat bracket installed by the dealer which made no difference ( i wasn't really expecting it to) and now I am at a fork in the road.

I have already invested a significant amount of money into this exhaust and want to try to make it work. So i decided to post here to see if anyone has any thoughts. There have been a couple of times I have driven the car with it being really loud and resonating and after 40 minutes on the highway at a constant speed, it is quiet and sounds like it should. So I know it should work.

My thought is that maybe there is an issue with the stock cat. I just was reading about issues with the stock cats after 30k+ miles which my car is now at 40k. If part of the internals in the cat were loose, could that cause a resonance? The cat is still the only thing left after reverting the header and air intake back to stock - both of which made no change in the noise level of the exhaust.

I would just hate to buy a replacement OEM cat just to find out that isn't the problem, but at the same time I would hate to go back to stock exhaust as the few times it has worked, it has sounded amazing.
 

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(I'm not a cat person - see posts on the clogged cat problems. lol)

I'm still a noob, but I'll throw this out there though I don't believe it's a likely contributor, just a possibility.) When screwing around with the stock cat, I had it off and was going to blow compressed air through it. I noticed when I picked it up I heard a "clank" and realized something shifted inside of it. On the inlet side it appeared that there was a separate ring with a mesh in it on top of the honeycomb that makes up the majority of the guts. When my cat problems started, I could hear a metallic rattle during shifts that almost sounded like a heat shield vibrating. After about 5 minutes of driving the noise was gone, I assume because that ring expanded and no longer floated around.
 

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I am not an expert on this, but on their site they do mention that the exhaust / cat / header combo will bring the level of " noise " up. I ran my car without and exhaust for a couple of days, ( oem cat) and to me it sounded nice. I was very loud, but with the exhaust being under the car that is a given. My friends decided it would be "cool" to gut the car while i had the car at their shop, and it has been nothing but a noise maker since then. To my personal opinion the cat plays a huge role in noise making. the C.A.I should not effect the exhaust note, it just makes noise under the hood. My car has 50k miles on it as we speak. Before the cat was hollowed out the car had a very nice sound to it. I would go back to the stock cat, and see what that will do for you. You also stated in your post " The cat is still the only thing left after reverting the header and air intake back to stock - both of which made no change in the noise level of the exhaust."
does this mean you are on the stock cat? You mentioned before that you had the HF cat installed. If you are not on the stock cat, go ahead and switch it back. It won't hurt to try it. Just my 2 cents. By no means am I an expert on this.
 

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Discussion Starter #4
Thanks for the responses...

Chickenwire- I did read the thread on clogged cats and that is where I got the idea that the stock cat may be defective. However I don't hear a rattle like you described nor do I have a loss of power as that thread implies.

BlueMotorsport- The stock cat is currently on the car. I had the hi-flow cat installed when i had all the performance parts originally installed. However after the first week, I had the OEM cat reinstalled due to the car being really really loud. This brought the noise level down a little bit, but also introduced this resonance. It was a bad choice on my part to use to say that cat was the only thing left. I didn't think that the air intake would affect the noise, but someone here in another thread did mention that the CAI can introduce a resonance into the exhaust. I figured I would try to figure it out - which obviously made no difference. Even reverting the header back to stock made no change in noise. That is why I was lead to think of the cat. The fact that the reverting the hi flow cat back to stock barely changed the noise level made me think that something may be wrong with it. At this point I am just grasping at straws before I pull it off and go back to stock. I know that Jeff at solo told me to bring it down to their shop in Buffalo, but it is just a long drive there.
 

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Thanks for the responses...

Chickenwire- I did read the thread on clogged cats and that is where I got the idea that the stock cat may be defective. However I don't hear a rattle like you described nor do I have a loss of power as that thread implies.

BlueMotorsport- The stock cat is currently on the car. I had the hi-flow cat installed when i had all the performance parts originally installed. However after the first week, I had the OEM cat reinstalled due to the car being really really loud. This brought the noise level down a little bit, but also introduced this resonance. It was a bad choice on my part to use to say that cat was the only thing left. I didn't think that the air intake would affect the noise, but someone here in another thread did mention that the CAI can introduce a resonance into the exhaust. I figured I would try to figure it out - which obviously made no difference. Even reverting the header back to stock made no change in noise. That is why I was lead to think of the cat. The fact that the reverting the hi flow cat back to stock barely changed the noise level made me think that something may be wrong with it. At this point I am just grasping at straws before I pull it off and go back to stock. I know that Jeff at solo told me to bring it down to their shop in Buffalo, but it is just a long drive there.
I understand your frustration, i have had issues with other portions of my car, but the companies i have done businees with have been nothing but patient with me. Jeff is a great guy, and we have made purchases for other parts from him before. As i don't know how far the drive would be for you, i can also understand the fact that you don't want to drive to buffalo. We are based in FL, and would not be able to drive up to buffalo just to get an exhaust checked out for my or even a customers car. I myself always look for excuses to drive my car. The main issue seems to be with the exhaust ( catback) itself. What i would reccomend, ( if you are doing the labor portion on your own) just put the stock catback back on, with the HF cat and the header and see what you get. If you have anobody that is local with a different type of exhaust, ask them if they can come over and switch it out for a couple of hours. Should not be to hard with a couple of beers. My personal car has 2 sets, and it only takes about 15-25 min to change them out. This could also be less time if you have a lift for the car. From what i've read, you ruled out the HF cat and the header being the origin of this issue, so the only thing left is the catback itself. If jeff is willing to ship out another system i would try that. It doesn't hurt if you tried it, it would only consume more time. I know how bad things can get. :willy: Hope you find the problem.
 

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Discussion Starter #6
Actually Jeff did ship out the other system to me and I installed it at my friends shop. It seemed to be quiet for 2 days (probably as it was breaking in) then began to sound like the previous kit. Jeff's thought was maybe there is something wrong with my car being unable to handle this exhaust kit. The other idea my friend had was to reinstall the HF Cat and see if I get the same resonance in those specific rpms/ coasting. Thanks for your help!
 

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Actually Jeff did ship out the other system to me and I installed it at my friends shop. It seemed to be quiet for 2 days (probably as it was breaking in) then began to sound like the previous kit. Jeff's thought was maybe there is something wrong with my car being unable to handle this exhaust kit. The other idea my friend had was to reinstall the HF Cat and see if I get the same resonance in those specific rpms/ coasting. Thanks for your help!
first off the SQR2 will be loud ... that is a given ... and each person has a different tolerance for"loud" ... I had the SQR2 on mine before I dropped the V8 in ...loved the sound ... as others have said Jeff is all about customer service ... I have heard some have installed a different resonator ... Jeff can help on that ... I don't know where you are located but another possibility is to go to DDMWorks in Piedmont, SC ... they are a SOLO distributor and are one of the best people to deal with ... so contact Dave at DDM and see if he can assist.
 

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Sounds to me like it's loosening up on you and developing a little bit of a leak somewhere after 100 miles or so. Sometimes those leaks will seal themselves as the car/exhaust warms up, so that might explain some of your symptoms too. Jeff had told me it tends to mellow a little as you start to build up the carbon inside, so it shouldn't be getting louder after 100 miles.

I had all combinations of the Solo header/cat/SQR-II. My experience was that with the hi-flow cat it was too loud for me. Header didn't seem to make much difference, but just before I sold the car I put it back to stock cat and manifold with the SQR-II and it sounded great.
 
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