AWE cat pipes installed...but....rasp?

[Andre5]

Go to your local Pep Boys and pick some exhaust paste. This did the trick for my install

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[Nexus-6]

Good idea - I've used something similar in the past on various motorcycles (muffler repair paste) to seal joints if necessary - just hate to use it as it's a real mess if you ever have to break said joint loose at some point in the future.

On top of trying the muffler loosen 'thang, I may swing by the local dealer and pick up a pair of new exhaust sleeves. My car has a few miles on it, and it's possible the old original sleeves are set in their ways, so to speak...

[machina]

Definitely get new sleeves. They seem to conform to the unique profiles of each muffler/cat union and it is a cheap and quick test.

The cats could be the culprit. I think there is a reason that they are only warrantied for 1 year and only to the original owner.

I bet AWE would check them out for you and possibly replace the elements if necessary. They have an even newer HJS section now that has a new type of coating that is more efficient.

[Nexus-6]

Quick update here - the fine gents at AWE have made some excellent suggestions on what may be causing the awful noise, and I'll be checking things out tonight. #1 on the suspect list is a loose or broken muffler baffle, and this makes a lot of sense to me considering the sound I'm hearing. OEM cans with lots of miles - completely within reason that this could be it.

But I did want to let folks know that even though I'm not the original customer, they are taking the time to help me in any way they can. That is simply fantastic and actually means a great deal to me these days.

[Nexus-6]

Howdy folks - looking for a bit of feedback as I continue to troubleshoot.

AWE suggested that it may be the mufflers themselves - a loose baffle. Not unheard of it appears in searching here on both vanilla variety C2S and PSE mufflers. My '05 C2S has more miles than most, 56,000.

I tested the mufflers via the good shake method and hear nothing loose. Before removing them, I tried to replicate the decel rattle that others have posted on loose baffles and didn't hear anything. It's possible that it's a baffle that's loose, but not loose enough to rattle with the stock cats in place.

So, right now, I have two mufflers and two cats that do not rattle when off the car. Short of x-raying them, I'm unsure of how to diagnose from this point forward. I have not yet reassembled with new sleeves (arriving tomorrow) - but about the only thing I can think of to eliminate one or the other is to replace the OEM mufflers with replacements. Before I waste AWE's time, I figure I'll replace the mufflers to at least rule that out before returning the cats.

Does anyone have a pair of C2S cans sitting around gathering dust? I figure while everything is off the car, I'd like to just try that before using (wasting) the new sleeves and clamps on the original cans. If it still rattles with new clamps and new(er) mufflers, I'll feel farily certain about returning the cats to AWE for diagnosis and replacement if neccesary.

Anyhow, please PM me if you happen to have a set of mufflers lying around that I can purchase from you.

[Ian_UK1]

Originally Posted by Nexus-6

Hi folks,

I installed a set of AWE cat pipes last night on my '05 C2S. Stock headers, stock mufflers.

Volume levels were expected, but the raspy nature of this change was not. At first, I suspected a leak at either the header flange or muffler 'sleeve', but everything is airtight (checked hot and cold).

My research via search tells me that swapping out the headers for either AWE units or x51s would solve (or at least reduce) this issue. Am I on track? It appears that headers + sport cats with the stock cans is the way to go with this issue, versus stock headers + sport cats and aftermarket cans for instance. Please correct me if I'm mistaken here before I spend more $.

I'd love to splurge on the AWE headers, but can't justify the price difference over the Suncoast offering (x51 at half of the AWEs) at the moment.

Primarily I'm just interested in eliminating the part throttle rasp/nasal tone I'm hearing between 3K ~ 4K, not looking for more power or volume at this point.

FWIW, full stick WOT sounds fantastic. It's simply that 3K partial throttle tone that had me, sadly, short shifting all day to avoid that range as it sounds rather obnoxious IMO.

I once had this same combo on my car (for a VERY short time) and can confirm your experiences are exactly the same as mine - it sounds like a trash can full of ball bearings at mid rpms. Horrible.

Unfortunately just replacing the stock headers (as I did at first) makes no difference to this sound. Sorry! Slightly different tone but still the ball bearings at 3-4000 rpm. And just to make things worse, using the stock header with AWE's cat/muffler combo is incredibly boomy but adding the headers fixes this nicely. AWE's cats simply work best together with their mufflers and headers. Mix and match isn't really effective.

[Gundo]

Sorry to hear about the issues you are having with the cats - when they were on my Cab, they worked fantastically well - no rattles, rasp or leaky sounds what so ever. Top down under all load scenarios resulted in just a really nice, deep, exhaust note. Nothing like a Civic with a fartcan. There are enough guys running the AWE cats here that we'd certainly heard similar complaints.

My setup was X51 Headers, AWE Cats, PSE. The stock Porsche clamps are pretty easy to install, and the extra set of clamps I put in the box were in good shape. Anyway, it sure sounds like you've got enough experience installing exhausts that this shouldn't be the issue.

If indeed the cats are somehow damaged internally, ship them back to me, and I'll give you a refund for your purchase price. I doubt UPS could have damaged them given the care taken in packaging, but you never know.

You are right - they weren't cheap, and they should be as described.

Sincerely,
Gundo

[Todd/AWE]

We've confirmed these cats to be the latest 200 cell HJS units by the serial tag. The chance that they are actually damaged is very, very slim. UPS would have had to run over them with a truck to damage them internally during shipping, and there would be obvious external signs of that. Plus, no cat codes or CEL are present.

We have installed countless of these cats in house, in combination with all sorts of other headers and mufflers, and have yet to hear what may be referred to as a rattling noise during operation. However, anything is possible given how freer flowing our cats are and how that may "excite" some of the baffling in the OE mufflers, producing a momentary harmonic. Without an actual sound bite, we are doing our best to help.

Nexus, we're not looking to upsell you, but if you are indeed looking to upgrade your mufflers, let's see what we can do for you.

[NorthVan]

Originally Posted by Gundo

My setup was X51 Headers, AWE Cats, PSE. The stock Porsche clamps are pretty easy to install, and the extra set of clamps I put in the box were in good shape. Anyway, it sure sounds like you've got enough experience installing exhausts that this shouldn't be the issue.

I have a very similar setup with the Evo Header, AWE Cats (old style) and PSE. I love the sound, get a lot of compliments and can switch the PSE's to sport and make the exhaust really loud. I can run on the track with out black flagging for excessive sound (unlike others at the track yesterday).

I would suggest adding some headers, and leave your OEM mufflers as is (for now) and see how it sounds.

[Ian_UK1]

Originally Posted by Todd/AWE

We've confirmed these cats to be the latest 200 cell HJS units by the serial tag. The chance that they are actually damaged is very, very slim. UPS would have had to run over them with a truck to damage them internally during shipping, and there would be obvious external signs of that. Plus, no cat codes or CEL are present.

We have installed countless of these cats in house, in combination with all sorts of other headers and mufflers, and have yet to hear what may be referred to as a rattling noise during operation. However, anything is possible given how freer flowing our cats are and how that may "excite" some of the baffling in the OE mufflers, producing a momentary harmonic. Without an actual sound bite, we are doing our best to help.

Nexus, we're not looking to upsell you, but if you are indeed looking to upgrade your mufflers, let's see what we can do for you.

I agree with you; that's exactly what's happening. When I was running the same setup as Nexus, there was an almighty resonance inside the standard cans when used with your cats and it pipes-up (please excuse the pun!) at 3-4000rpm. It sounds as if the insides of the mufflers have disintegrated and are rattling around in the cans!

When I had this issue, replacing the Porsche cans with your mufflers put everything back to how it should be, proving your cats were fine. I've also had the complete standard system back on the car again briefly since (to go to the local stealer) and that proved there was nothing wrong with my standard cans either.

I doubt Nexus has an issue with his cats or Porsche cans - as you correctly say, it's just the much more open nature of your cats that interacts oddly with the standard Porsche items.

[///MJFDDS]

I think a sound clip would be helpful. If your exhaust sounds similar to us that have the same set ups, then it just may be that you dislike the sound that the AWE cats add to the exhaust note and there may be no problem at all.

[Nexus-6]

Ian,

I think this is precisely what's happening. I'm sure with new, matching AWE headers and cans, it would sound fantastic.

I spent most of the early morning reinstalling everything by the book - taking a great deal of time to torque everything back to front precisely, new gaskets again, new sleeves and clamps this time as well - all joints cleaned and smooth. Alignment was much better with everything loose this time around and I hoped for a change.

No change though - same results.

As the my C2S is my daily driver, I wanted to hold off on any exhaust work as I commute quite a bit. All the weekend toys are loud, but I've managed to and wanted to keep this car quiet. The cat pipe swap was done simply because it was easy to do, and somewhat cost effective for the gains (especially when buying used).

But with the stock headers and stock mufflers, it does not sound good. Frankly, it sounds horrible. Ian's description of what I'm hearing is exactly what it's like. I stgruggled early on to describe the sound, but he's nailed it. No offense to anyone who has this setup, but it's not pleasing in the slightest to me. I decided to go for it as there are many folks who have posted that this combo is fantaestic. Do remember that it's stock headers and stock mufflers...some of you have said that you have no issues with this setup, but then go on to mention X51 headers and/or PSE...here, 100% OEM headers + 100% OEM (base) mufflers + AWE cat pipes does not make for a pleasant tone.

The good news of course is that there isn't a problem with these cats. AWE designed them to work as part of greater whole in their full system, and while they do work with stock bits, it's not a song I find pleasant.

Given the two options I have in front of me - going for the full meal deal or back to stock, I think I'll have to suck it up and go back to stock. I hate to, as the gains are nice, but the car does not sound the way it should. I've "cheated" on my personal budgets before in regards to exhaust on other cars...way too many times in fact...and this time I think I just hang my head and chalk it up as an experiment. On the bright side, the exhaust is now thoroughly cleaned, checked and tightened with brand new clamps and gaskets!

Before I take them off, I'll take a video of it and host it. I can replicate it in neutral I've discovered so I can capture what I'm talking about to some degree (under load, it's louder and more nasaly but the "essence" of the sound I'm hearing comes through loud and clear whilst revving in neutral). Perhaps this will give folks who are coming into this same decision gate a bit more data to help them decide if it's right for them. I'll have the cats off in the coming days and available if anyone wants them.

Thanks again to the AWE guys and for all of the great insight provided here by other members - much appreciated.

Originally Posted by Ian_UK1

I agree with you; that's exactly what's happening. When I was running the same setup as Nexus, there was an almighty resonance inside the standard cans when used with your cats and it pipes-up (please excuse the pun!) at 3-4000rpm. It sounds as if the insides of the mufflers have disintegrated and are rattling around in the cans!

When I had this issue, replacing the Porsche cans with your mufflers put everything back to how it should be, proving your cats were fine. I've also had the complete standard system back on the car again briefly since (to go to the local stealer) and that proved there was nothing wrong with my standard cans either.

I doubt Nexus has an issue with his cats or Porsche cans - as you correctly say, it's just the much more open nature of your cats that interacts oddly with the standard Porsche items.

[Nexus-6]

Originally Posted by ///MJFDDS

I think a sound clip would be helpful. If your exhaust sounds similar to us that have the same set ups, then it just may be that you dislike the sound that the AWE cats add to the exhaust note and there may be no problem at all.

I'll be taking a clip this afternoon.

To be clear here, I don't have the same setup as you or some others - I'm certain the X51 headers + PSE make a substantial difference in tonal quality. I have OEM headers and the base level exhaust. I've heard the PSE + cats combo and it sounds nothing like what I've got (which is a good thing for you!)

[Nexus-6]

I forgot to mention - Gundo, the cats were packaged perfectly. No worries there! There's no way they could have been damaged I don't think given the packing job you did. Thanks for that.

Also, thanks for offering a refund if the cats were in fact bad. In my case, it's simply the rest of my OEM system that appears to be the issue. But your offer is truly generous and stand up - thanks!

[Dave07997S]

Nexus going with the X51 headers is not going to change the harmonics of the OEM cans. You need to switch out the mufflers. When I did my exhaust I did the AWE cans first then the X51 headers and harmonics barely changed.

Dave