What about the garageline exhaust? It's looks like a higher flowing version of the OEM exhaust. Unfortunately I don't think a ton of people on here have it... It is very cost effective too!

Also, I think it would be a good idea for the OP to give Sebastian a call regarding a solution as a 3" down pipe and exhaust could potentially impact performance negatively because a SC doese need some back pressure to make optimum power so it's a catch 22!

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Stock cats for now.

That is why it sounds so good. The best sound I ever heard coming from a Z was when I had the stock cats with FI exhaust. Take those cats off (because boost) and its a total game changer. They act as 2 giant mufflers.

Your cats will eventually blow out on you.

Because it has cats.

Cats that were designed for forced induction.

And turbos. They make an enormous difference.

Ok... That's the point I'm trying to understand. I take it there's no aftermarket cats he could throw in there that would help?

Not in the stock location if he is going to boost. They dont hold up very well.

I feel like there must be something that can hold up to it. I have seen on the Scoobie forums folks have used Magnaflows with good success.. Z1 sells a "Thunderbolt" cat that they believe will hold up to the abuse. (They use them for Z32, but I posted a question to the product page about using on a boosted 370z and they think it will work)

I'd like to see some other boosted platforms in terms of how far upstream they mount the cats... It may be as Topz says and the stock location is just too hot.

I suspect, however, that the data we have in this forum is probably related to the bolt on options we have available, and I am pretty sure none of those are up to the task to dealing with FI. I feel like there must be some weld-in options that will work... just based on other platforms having options.

Sebastian recommends ART pipes ten out of ten times, which are 2.5" same as the FI resonated pipes I have on right now. We've chatted about this several times.

I love the ART/Shockwave combo. But from experience it can be varied in noise level a LOT based on air going into the engine. NA example it was actually pretty quiet last summer when I had the Stillen G3 intakes on, whereas it was pretty damn loud with the Injens. That's changing nothing except the intakes.

Knowing that I really couldn't say how loud or quiet it would be with the blower and air to air setup. I suspect given the shear volume of air coming in it would tend to be on the loud side with reasonable certainty. That said, I also don't know exactly how loud the FI res pipes and shockwave combo will be with the air to air yet either. I do know that with my current setup (modified Stillen piping) it is damn loud. Much too loud.

I emailed Mariella at Motordyne a few days ago and haven't heard back yet. There are mid-pipes between the X and tailbacks that are straight with nothing more than a hangar on them. They do offer individual components like resonators and various cats but I'm not sure if any of them are a direct replacement for these mid-pipes. I'll update with her response when I receive it.

That's also the same spot I've been considering for downstream cats that I could just cut and weld in. Somebody a whole back had posted a link to some 200/300 rated aftermarket HFC (think it was jayhova) so those might be worth trying out.

With the current setup, the motordyne exhaust and OEM cats are a great sound sound and basically what I'm after when it's all said and done. So basically the goal here is something along those lines.

I did look into the CNT exhaust and it is backordered all over the place. I found one set with the blues tips (which I don't like but can change easily enough) but he wants about $200 more than CNT does for it so that's not going to happen.

In short, no resolution yet but there's some good suggestions floating around now that the conversation has been started and I'm sure something will come of it.

That's the issue for sure. Though your comment reminds me of something else Sebastian mentioned to me over the winter that you can weld in some metal substrate before the OEM cats to absorb and dissipate the heat to a degree before it gets to the cats. Like welding in a metal X or something inside the pipe.

For reference here is the shockwave exhaust, and the straight sections I mentioned for the cats circled
http://www.the370z.com/members/chase...5-img-3785.jpg

Yo Chase, you may want to check out ssfirehawk's old build thread as he is the one I was talking about that had the gtm twin SC setup along with the motordyne exhaust system. He had ppe long tube headers so I think would be as loud as it would get. He is still active on the forum and I know he did some videos. I know it hard to tell but can give you some indication.

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Thanks, I found it and it's a biggy so dropping a link here so I can read it later

http://www.the370z.com/members-370z-...a-project.html

Who cares about your neighbors? I have neighbors with mustangs and corvettes and harleys with loud exhausts. It's part of the city noise.

When you see cops, just keep it below 3K rpms.

I'm looking to switch over to motordyne to eliminate all the drone from my FI exhaust setup. Have side branches resonators but still has some drone at highway rpms. A lot better than before though.

Anyone try the CNT ART/HKS style test pipes?

This is exactly what I did. Made little difference.

I installed a pair of these:

Considered these HFC in that spot, and they are supposed to be good but I'm not sure I want to drop $250 usd plus install to find out.

http://www.ebay.com/itm/110847989857...torefresh=true

Trust me, they'll be even worse. Take a look at the dimensions of that one, and then these:

Magnaflow 3" 200 CPI Metal Core Stainless Steel Cat Catalytic Converter Oval New

These are exact one I bought. They're longer & wider, and like I said they didn't have too much of an effect.

When you say that "they didn't have too much of an effect," do you mean on boost pressures (i.e. restricting the exhaust and increasing boost), or on sound levels, or both?

GESI makes a nice high quality drop in cat that will withstand the high egts from boost. i know Seb tuned a nismo 370z with these cats on a stillen sc and had good results.

link https://www.vibrantperformance.com/c...Path=1527_1326

Based on the discussion in this thread, Chase, I think you should probably just add some turbos. :tup:

Bringing up the GTR exhaust again, just as an example. It has two sets of cats and a "Y" pipe, etc... Hell, if it takes this much engineering to reduce the sound, just remove the SC. You built a race car and it comes with a certain decibal level... LOL

https://farm3.staticflickr.com/2867/...77688f_z_d.jpg

Sound level. Didn't notice any difference in power/boost at all.

Jeez, for those prices you might as well just buy another whole system! :confused:

I've got 2 Vibrant GESI 7530's. They are placed at the end of the downpipes close to the flange.

It hurt the wallet but I'm hoping to not have to replace these. Sounds good with a 3" exhaust, etc.

Sounds good. Send me yours :tup:

I built this a long time ago for my 350Z:

http://i137.photobucket.com/albums/q...ps38034bdd.jpg

http://i137.photobucket.com/albums/q...ps1df5f7db.jpg

http://i137.photobucket.com/albums/q...ps6b092cbd.jpg

The two mufflers in the rear were very large straight flow through design, and for that reason along with the turbo, the exhaust was as quiet as stock. This is with aftermarket equal length headers, and of course no catalytic converters.

I have since built this:

http://i137.photobucket.com/albums/q...pslijhbqjm.jpg


3.5" piping from where the OEM Y-pipe would end, splitting in to dual 3". This is all aluminium, and weighs in at 12lbs. It is of course louder, but not as loud as one would think.

Also did a single 3.5", which is a bit more rowdy :) it came in at about 8lbs :

http://i137.photobucket.com/albums/q...pscmtlm5ad.jpg

http://i137.photobucket.com/albums/q...ps1kc9x1em.jpg


Sound clip of the single 3.5" splitting in to dual 3.0"

http://vid137.photobucket.com/albums...psueffzhrq.mp4

Sound clip while on the lift single 3.5":

http://vid137.photobucket.com/albums...pscleukp0r.mp4

Love that first one, any clips of that one?

And for the size I was expecting a lot more noise for those last two. Nice work!

I'm waiting to finish rebuilding my SC, before I do another recording under the same circumstances of my pre-SC recordings for a reasonable comparison. Right now the car starts, but the SC is on my bench awaiting new seals & bearings hah.

Sorry, don't have sounds clips of the first one. It is basically stock sounding. With that exhaust, all you hear is the turbo.

Ditto. Got my new seals and bearings here just need to get to the R&R.

Maybe I need a 3" test pipe instead of 2.5

Or bring my car up a couple days before seb's dyno day in June and you can whip me up an exhaust like that one..

Dang Sasha. You should start a BP exhaust option with your kits, or others. Those look great!

For sure, I'd be able to help you with that.

Go full aluminium once you are out of the heat range of the turbo, I really like the tone on my own car. Dual 3" with 4 mufflers.

I also use 3mm wall aluminium tubing on the exhaust, not the typical Vibrant paper thing crap. It will last a very long time.


Yeah, I had a bit of a feeler for the aluminium exhaust, but there wasn't all that much interest.

But then my car will be too loud!

I thought I was understanding that the consensus leans towards turbos being generally quieter than s/c (although depending upon a host of variables), but in this thread it seems that turbo and s/c exhaust systems are being compared interchangeably.

If there IS a difference in sound levels between the two systems, how can the s/c exhaust be modified to reduce some of this additional noise? Maybe I'm in the minority, but I'd like to see some configuration that keeps the decibels to a manageable level. Seems like the cats are a key component to reduce some of the worst of the noise, but they should be repositioned downstream to avoid the worst of the heat? Is that right? Where would you place hangers, etc.? Will the sensors need additional cabling to reach? Other problems?

I found a suggestion on one website that recommended adding spiral inserts inside straight pipes to reduce excessive noise. Has anyone tried something like this?

I tried Googling the images of the exhausts of factory s/c cars, but that didn't really yield helpful results. Are factory s/c cars known to burn through cats?

There is definitely a difference in noise having turbos in the exhaust stream and its a very significant one. Exhaust sound, heat, velocity... energy in general, are soaked up by the turbo.

There is a lot of good discussion on this thread.. but for the sake of discussion we've probably overthought it quite a bit (which is healthy as it helps us all gain more knowledge....one of the primary purposes of this forum!)... I think if you just go with one of the quieter exhaust systems that follow the OEM design (allows for much larger muffler) and some resonated test pipes (or cats somewhere in the stream), you'll be fine.

To that point there are a couple of other options for exhaust systems out there. The Nismo S Tuned a little better the oem a just a tad louder and I would be curious how the aam 2.5 " dual mide pipes attached to the back section of the Nismo exhaust would work. That muffler on the back of the Nismo exhaust really knocks down the sound.

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I have access to a Nismo exhaust. It would be pretty restrictive though wouldn't it?

Yes... that is why I would get the aam mid pipe to mate to it. Or you could have a custom mid pipe made. The last section of Nismo exhaust is 2.5" I believe.

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:iagree: 2.5" is probably all you want anyway... Being SC you still get scavenging benefits of back pressure like an NA car would (as opposed to turbo cars which benefit from the least restriction possible after the turbo).

I also think the Garageline exhaust would be a good alternative as well, and it is modular I think (flanges between parts take place in factory locations...), so you can mix and match parts like mid pipes, y/x pipes, axel back. (and its cheap).