CaymanSinAR

Clearly one of the best things about the GT3 is its 9K redline. The 4.0 is probably the biggest factor in terms of why I bought a GT3. But if I have one complaint it is that the factory exhaust note doesn't particularly come alive until well into the rev range (especially in the cabin). The reason this really stands out to me is because my 981 Boxster GTS doesn't have the same issue. Inside or outside the car, the 3.4 in my Boxster GTS sounds extraordinary from the second you turn the key. Idle? Fantastic. Accelerating to 4K? Sublime. 4K to redline? Glorious wailing perfection. And that is without even engaging PSE.

Don't get me wrong; nothing I have owned in the past or likely will own in the future will match the GT3 at full chat approaching 9K. That alone is nearly worth the price of admission. But in everyday driving at more normal rev ranges the exhaust note of the GT3 is not as pleasing as the GTS. Why? I'm guessing there is something about the nature of naturally-aspirated flat sixes that favors smaller displacement in terms of exhaust note. I'm not mechanically inclined though, so I figured I'd ask just to satisfy my curiosity.

Dr.Bill

The Boxster GTS has the sound symposer that pipes engine noise into the cabin. The GT3 does not.

Listen from outside the car and the winner will be clear.

RossP

I disconnected the vacuum lines for the bypass valves so they stay open all the time, and added a sharkwerks center muffler delete. Transformed the car.

CaymanSinAR

True on the sound symposer. Odd the GT3 forgoes it as it certainly helps the interior noise of the 991.2 and 992.

But to me the GTS still sounds better than my GT3 and GT4 from idle to redline as a whole (inside or outside the car). For that matter I prefer the GTS to the GT4 at any rev range. But the GT3 past 7,500 is unmatched.

CaymanSinAR

Mine were oddly somehow stuck closed when I got the car. My indy fixed that straight away. The first thing I do when I start the car is open the exhaust. Oddly the GT3 has to be started in order to do so; the GTS and GT4 can be enabled before the engine is running.

I'm considering a GMG center bypass.

rob944s2

Don’t hesitate to do the bypass, I think it’s the best mod you can make. My theory is these cars were intentionally designed to be very easy to remove the center muffler to install a bypass. It sounds so perfect with a center bypass that I truly feel it’s what the designers intended most everyone to do, where legal. If you keep the side mufflers and leave the valves connected you get crazy sound when you want it and no highway drone when you don’t.

So my answer to your question is that the GT3 sounds quieter than your 981 because the GT3 isn’t really intended to have that center muffler in the 1st place and it’s only there for regulatory compliance and the intended configuration is with a bypass, which is why they made it so easy to do. No offense to the side-delete and full header guys.

CaymanSinAR

Very interesting take. Thanks for that.

Jimmy-D

GMG Bypass and disconnect your valves will do the trick.

But - glad they do not have the Sound being piped in because I always drive with windows open and it would be too much in my opinion

CaymanSinAR

I'm about to do a search for "bypass" but as a quick question is there any real difference between the center bypasses offered by GMG, Sharkwerks, Soul, etc?

ugotgrossed

how's sharkwerks by pass vs sharkwerks track exhaust? Which sound better

bigdog1250

Yep, disconnect the vacuum lines as they close up the exhaust at odd times and ruin the sound down low. Then once you add a center muffler bypass, you'll be good to go. I went with the Fabspeed system and can't say enough good things about it, even made a youtube video review:

bigdog1250

They are all very similar, main difference is:

1) Price
2) The shape and location of the balancing tube that connects the two sides. Fabspeed's is most similar to the OEM setup which I liked

They're all gonna sound pretty similar, so can't go wrong with whatever you choose

John Ferguson

IMO GTS 3.4 cylinders emit a higher pitched wail due to their smaller bore. Put Fabspeed race headers / pro tune on my 981 GTS and get lots of attention from other pcar owners at events. I too prefer my 981 GTS sound over GT3 sound, inside and out, and the top goes down to boot!

C5driver

In spite of certain accommodations to comfort, GT cars are supposed to be more raw and track-oriented, so something as artificial as "fake" sound may not be within the spirit of the GT division.

ipse dixit

Because GT3 only sounds good at about > 7500 RPM