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Subscribed. I need a catted system that will pass sound at Laguna Seca and stand up to extended lapping. There have been some premature failures of catalytic converters on cars that have seen extended track use.
I would be glad to help test sound levels and report back if this information would be useful to you.
So far our cats have held up well, but generally even metal core cats don't do well for a long time at the track. Our recommendation for those that want a catted system is to run the test pipes for track days and cats when back on public roads.
I'll PM and see if we can coordinate something. Laguna numbers are always helpful!
Dundon Prototype Convertible Catted Valved 321SS Exhaust Tip Pics
Looking good Jamie! So are you guys still testing different insulation, sound tuning, drone issues, etc?
Still very curious about db levels compared to stock throughout the rev range. In my case, I would probably be doing the "quiet" version without cats, mated to my current race headers!
Also, is there a reason for not doing an x pipe style tip section (post muffler)? Assuming its to allow for swapping to turndowns...
Looking good Jamie! So are you guys still testing different insulation, sound tuning, drone issues, etc?
Still very curious about db levels compared to stock throughout the rev range. In my case, I would probably be doing the "quiet" version without cats, mated to my current race headers!
Also, is there a reason for not doing an x pipe style tip section (post muffler)? Assuming its to allow for swapping to turndowns...
We're working on a specific resonance with the cats/race header combo. We don't find it with the stock headers and rear section test pipes, need to test with the race headers and test pipes in the rear section.
The way we have it designed the rear pipe is where the two waves crash into one another.
The quiet version is what we've been testing and at the track and it's about 10-12dB quieter. It's a little quieter at idle as well. The resonance between 2000-2500 with the Race Header/Catted rear section combo (the one we think will be popular) is what we're working to dial out.
We will get the test pipes in it here shortly and test that for dB reduction as the cats do help kill some dB (2-3db or so we estimate).
We also need to test on a stock header car for dB reduction as there are quite a few that are interested in trying to pass sound at Laguna and others.
Last thing we're looking to try is to see how our GT3 mufflers do on the GT4, we've designed a bracket to hang the GT3 muffler on the GT4 and support it well, could be a nice option.
We're working on a specific resonance with the cats/race header combo. We don't find it with the stock headers and rear section test pipes, need to test with the race headers and test pipes in the rear section.
The way we have it designed the rear pipe is where the two waves crash into one another.
The quiet version is what we've been testing and at the track and it's about 10-12dB quieter. It's a little quieter at idle as well. The resonance between 2000-2500 with the Race Header/Catted rear section combo (the one we think will be popular) is what we're working to dial out.
We will get the test pipes in it here shortly and test that for dB reduction as the cats do help kill some dB (2-3db or so we estimate).
We also need to test on a stock header car for dB reduction as there are quite a few that are interested in trying to pass sound at Laguna and others.
Last thing we're looking to try is to see how our GT3 mufflers do on the GT4, we've designed a bracket to hang the GT3 muffler on the GT4 and support it well, could be a nice option.
Thanks for the detailed response! Im anxious to get something to quiet my car down but dont plan on running cats.
Seems the GT3 muffler might be a good option as the body of the muffler seems bigger which I assume could mean potentially quieter.
In the original post you mentioned adding extra insulation for the "quiet" version. Do the ones you have been testing have the extra insulation, or are they "standard"?
Thanks for the detailed response! Im anxious to get something to quiet my car down but dont plan on running cats.
Seems the GT3 muffler might be a good option as the body of the muffler seems bigger which I assume could mean potentially quieter.
In the original post you mentioned adding extra insulation for the "quiet" version. Do the ones you have been testing have the extra insulation, or are they "standard"?
Thanks,
Matt
We have the option of adding/changing internals to get them quieter. So far all that have been tested are the "standard quiet" or what we're calling the Street GT3 Muffler. The Extra Quiet will be called the Laguna GT3 Muffler
Will you be measuring with the valves open or closed on the GT4? I'm assuming your valves function properly with the stock PSE controller on the car?
An exhaust quiet enough to pass sound at LS with the valves open would diminish the sound experience when running around on the street and other tracks.
If our current GPS PSE controllers can control the valves on your muffler and pass sound with race headers at LS (either with your tips or with sweeps) that would be a system I would have interest in.
Will you be measuring with the valves open or closed on the GT4? I'm assuming your valves function properly with the stock PSE controller on the car?
An exhaust quiet enough to pass sound at LS with the valves open would diminish the sound experience when running around on the street and other tracks.
If our current GPS PSE controllers can control the valves on your muffler and pass sound with race headers at LS (either with your tips or with sweeps) that would be a system I would have interest in.
So this is a bit of a conundrum. If we design a muffler so that it is only quiet enough with valves closed, this will only work on tracks where the sound booth is a known location (i.e. Laguna, Limerock). But many tracks around the world are getting wise to our ways and starting mobile sound checks, or random sound checks and then the muffler system dependent on a GPS valve closure to be quiet will fail.
What we have sketched out is a slightly different approach to our CCV muffler. One where you would be able to swap the muffler over easily and quickly from loud to "quiet" mode, no GPS valve solution necessary. This change would be done before a track day so that you can pass sound, then when track day is over, and you want a louder soundtrack, you swap back.
The CCV is still moving forward, as some want the car quieter (especially those with our Race Headers...) to not attract as much attention when out on the road.
So this is a bit of a conundrum. If we design a muffler so that it is only quiet enough with valves closed, this will only work on tracks where the sound booth is a known location (i.e. Laguna, Limerock). But many tracks around the world are getting wise to our ways and starting mobile sound checks, or random sound checks and then the muffler system dependent on a GPS valve closure to be quiet will fail.
What we have sketched out is a slightly different approach to our CCV muffler. One where you would be able to swap the muffler over easily and quickly from loud to "quiet" mode, no GPS valve solution necessary. This change would be done before a track day so that you can pass sound, then when track day is over, and you want a louder soundtrack, you swap back.
The CCV is still moving forward, as some want the car quieter (especially those with our Race Headers...) to not attract as much attention when out on the road.
My question/comments to the above are:
Define "easily" with regards to swapping the muffler between the 2 modes.
and (while this may be an urban legend) I've heard one of the reasons one just shouldn't simply physically wire the PSE valves closed is heat generation. Have you considered that aspect in designing an exhaust that stays closed full time? Laguna doesn't normally have high temp days but it seems like once a year it will get into the 90s.
Define "easily" with regards to swapping the muffler between the 2 modes.
and (while this may be an urban legend) I've heard one of the reasons one just shouldn't simply physically wire the PSE valves closed is heat generation. Have you considered that aspect in designing an exhaust that stays closed full time? Laguna doesn't normally have high temp days but it seems like once a year it will get into the 90s.
Easily as in changing the exhaust tips.
As the PSE wasn't designed to have the full flow of the engine through it with the valves closed, running it with the valves closed would cause the Exhaust temps to rise and possibly harm the engine.
A muffler that is designed to take the entire flow of the engine and disperse and absorb the sound energy won't drive up EGT's as the flow isn't compromised. And to clarify, I'm not suggesting that this possible design would be toggled by the PSE valve, I'm saying the PSE valve would still work, AND we would make the muffler configurable by making a mechanical change between loud street use and dB restricted track day use.
Full system package w/ race headers available for Rennlisters yet? Assuming fitment for my 981 Spyder.
Hi Nelson, Absolutely we can put together a package for you and it will definitely fit your Spyder. We just got back the CCV muffler from testing at Laguna and need to get it opened up for fixing the resonance. It's on the docket for next week to get it opened up and some design changes to fix the resonance with it. So for now we'll have to hold off, but in about 2 weeks we'll know better if we can release it finally!
Hi Nelson, Absolutely we can put together a package for you and it will definitely fit your Spyder. We just got back the CCV muffler from testing at Laguna and need to get it opened up for fixing the resonance. It's on the docket for next week to get it opened up and some design changes to fix the resonance with it. So for now we'll have to hold off, but in about 2 weeks we'll know better if we can release it finally!
Thanks Jamie, please keep us posted here. My Spyder is dying to take advantage of these mods. I've been looking for the right setup for a while.
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