A not-crazy-loud catback exhaust that keeps the OEM valve?

[Spart]

Probably more material in the stock vs hks. I've never cut my hks open but it sounds different.

Judging by this video, it seems like the difference in sound between valve open and valve closed is almost all down to the pops-and-burbles ECU map.

I want it to be heavily muffled when the valve is closed.

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[baagel]

I have the APEXi exhaust and love it. Despite looking similar to the HKS, it does sound different.

The valve exists to control noise level and droning. I think you're focused too much on the design of the piping. The stock exhaust is also identical on both sides of the exhaust, yet you still experience louder exhaust noises with the valve open. Think of it like covering one of your ears. Your ear canals are roughly identical but if you cover one, everything is much quieter.

Side note, Akrapovic is mostly more expensive due to them having completed emissions testing so it's CARB compliant and whatnot.
SARD is a JDM brand and all JDM brands are significantly more expensive.

 

[Spart]

SHS, just installed mine and it’s sounds pretty much stock valves open with the valves closed (I have an Aa catted dp which is an epa legal catted dp and no warranty issues with that or Cel. and with them open a nice deep sound that’s a decent bit louder then stock and more exotic sounding. Retains Oem valve and function and all made in usa. Inside video is with ASD disabled.

They don't list this on their website: https://www.shsautosport.com/products/A90-A91-c140962772

Can't really find any info on it or pictures.

 

[Spart]

The valve exists to control noise level and droning. I think you're focused too much on the design of the piping. The stock exhaust is also identical on both sides of the exhaust, yet you still experience louder exhaust noises with the valve open. Think of it like covering one of your ears. Your ear canals are roughly identical but if you cover one, everything is much quieter.

I think people are just kind of missing what I'm after. The stock exhaust sounds like there's hardly any difference at all between normal and sport to me.

On the GT350, when the valves are closed everything is going through a pretty aggressive muffler that makes the car reasonably quiet. Valves open, it's essentially bypassing the muffler. Its a VERY apparent difference when the valves open, both inside and outside the car.

Almost all the videos I've seen of Supra designs that retain the OEM valve don't seem to have hardly any difference in volume whether the valve is open or closed. And a lot of them also just seem loud all the time regardless of valve position. When that valve is closed, I want it to be as close to stock as possible with regards to volume.

 

[decodeddiesel]

Okay riddle me this about the HKS setup because it's been brought up repeatedly - maybe I'm just looking at pictures and not seeing what's going on. It looks to me an awful lot like the piping is the exact same after the Y on both the valved and non-valved side.

So if that's true, what difference are you getting in sound aside from the changes in the engine map to turn up the pops and burbles? Is the valve not just there to keep the car's ECU happy?

When that valve closes, I actually want it to do something. On the GT350, it may as well have been a mute button. You'd never know how loud the car could get when you were cruising the interstate at 75mph in 6th.

The 2nd "muffler" acts like a resonator/damper when the valve is closed. This should eliminate droning, "rasp", and amplitude (sound pressure levels).

The 2nd muffler also has a different internal configuration than the primary muffler and allows gas to move more freely through it when the valve is open.

Finally when the secondary muffler is open it effectively doubles the area the gas is allowed to flow through.

All of these combined add up to a significant increase in sound pressure levels when the valve is activated.

Keep in mind however that Japan has some serious restrictions on how loud an aftermarket exhaust is allowed to be and HKS had to conform to those standards to be able to sell their product in Japan.

If you want Jekyll and Hyde you can always get the Magnaflow exhaust and run it with a muffler on the primary side and a bypass on the valve side.

 

[jtsang25]

Judging by this video, it seems like the difference in sound between valve open and valve closed is almost all down to the pops-and-burbles ECU map.

I want it to be heavily muffled when the valve is closed.

The valve does nothing to the ecu or change mapping. It's basically like having your office door open and office door closed. You can have it removed and it won't throw CEL or effect anything.

 

[BA9092]

They don't list this on their website: https://www.shsautosport.com/products/A90-A91-c140962772

Can't really find any info on it or pictures.

I totally thought this was the Injen from the underside on the stationary video.

 

[Spart]

The valve does nothing to the ecu or change mapping. It's basically like having your office door open and office door closed. You can have it removed and it won't throw CEL or effect anything.

You're saying the sport mode doesn't increase the pops and burbles? That's a function of the engine map. And in these configurations where the OEM valve is being retained, they're using sport mode to open the exhaust valve. So you can't have one without the other...

 

[baagel]

I think people are just kind of missing what I'm after. The stock exhaust sounds like there's hardly any difference at all between normal and sport to me.

On the GT350, when the valves are closed everything is going through a pretty aggressive muffler that makes the car reasonably quiet. Valves open, it's essentially bypassing the muffler. Its a VERY apparent difference when the valves open, both inside and outside the car.

Almost all the videos I've seen of Supra designs that retain the OEM valve don't seem to have hardly any difference in volume whether the valve is open or closed. And a lot of them also just seem loud all the time regardless of valve position. When that valve is closed, I want it to be as close to stock as possible with regards to volume.

Unfortunately I don't have a good way to show this, but with my APEXi exhaust with catted aftermarket DP, there is indeed a significant difference between valve open and closed. And it's not because of the burbles.

It's hard to tell the difference in videos. You really have to listen carefully and even then it's not exactly what you would hear IRL. I spent more time than I'd like to admit trying to compare exhaust sounds through YouTube vids.

 

[jtsang25]

You're saying the sport mode doesn't increase the pops and burbles? That's a function of the engine map. And in these configurations where the OEM valve is being retained, they're using sport mode to open the exhaust valve. So you can't have one without the other...

You can bimmer code it so valve is always open or always closed. So you can have one or the other. Yes sports mode changes the mapping. But the valve on the supra can be unplugged while open and still have the changes when going from sport mode to comfort. I could bimmer code the valve to stay closed and still have the burbles of sport mode, it would just be muffled because the valve is closed.

 

[razorlab]

SHS, just installed mine and it’s sounds pretty much stock valves open with the valves closed (I have an Aa catted dp which is an epa legal catted dp and no warranty issues with that or Cel. and with them open a nice deep sound that’s a decent bit louder then stock and more exotic sounding. Retains Oem valve and function and all made in usa. Inside video is with ASD disabled.

sorry, what catback is that? SHS? Can't find anything about it. Looks like the injen catback in your videos.

 

[Spart]

You can bimmer code it so valve is always open or always closed. So you can have one or the other. Yes sports mode changes the mapping. But the valve on the supra can be unplugged while open and still have the changes when going from sport mode to comfort. I could bimmer code the valve to stay closed and still have the burbles of sport mode, it would just be muffled because the valve is closed.

I won't be doing that (any sort of mod to make it always open) - I specifically want the functionality of being able to change it with the sport button.

 

[Spart]

Just for reference (and yes I know this video looks like it was made in 2004, it's not mine ? ) if you skip to 4:22 you can hear a decent comparison of what the GT350 sounds like with the valves closed vs. open. It sounds like two entirely different cars.



Valves closed on the GT350 sounds even quieter in person, the automatic gain on the camera is probably compensating for how quiet the valves closed mode is. This is the kind of difference I'm after. Maybe it's not possible for it to be this extreme on the Supra and I get that, but it certainly seems like most of the designs for the Supra (other than the aFe and Borla) aren't really designed to have much difference in volume between valve closed and valve open.

 

[decodeddiesel]

Maybe it's not possible for it to be this extreme on the Supra and I get that, but it certainly seems like most of the designs for the Supra (other than the aFe and Borla) aren't really designed to have much difference in volume between valve closed and valve open.

That's not true at all. See my previous response to the question you asked me.

 

[jtsang25]

You seem set on the afe one. Why not wait for it. @decodeddiesel explained it nicely.

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