bovien

Has anyone noticed/experience with the difference exhaust note from different center bypass systems? I've had an X pipe that made a glorious sound at full cry, and also raised volume at more normal revs, but often resulted in a lower 'quality' sound at regular driving/slow acceleration. It resonated in the back of the cabin and a slight vibration-ish sound from interior panels was noticeable.
Will, for example, a Sharwerks system do the same?
I mean, the mezger sound is glorious by itself, but can be should sculpted 'high quality' like the OEM system, or a less 'quality' sound like straight pipes.
I'm looking for a bit more volume at regular driving but still with a quality of sound.

Makes sense?

voodoo

bovien

Sweet!
I've found lots of video, but it's hard to translate that to the sound in the driver's seat driving around.
Can you recognize what I'm talking about in regards to quality of sound and resonance in the interior?

pissedpuppy

the more I read a LOT of guys prefer the side muffler delete vs center muffler delete

better sound and lose more weight

The Greek

bovien

No go for me. That will delete the exhaust valves, which I need to be able to force closed at trackdays.
Drone is also no-go for me due to long motorway/autobahn stints to the ring

Center delete is my way, but I need to figure if I will get better medium range sounds with fx Sharkwerks vs the more-or-less no brand X pipe I got now

JB911

You can of course use velvet side deletes, there are a number of manufacturers that offer them. I thought of trying them with my stock center, or with my FVD/M&M center bypass. There's lots of info on cracked OEM center, mostly tracking I think. You can get OEM center reinforced to prevent this.
The TPC valved sides retain the flexible upper area of the pipes. Seems like originally they used the factory looking bellows for flexibility, which I think would help-they seem to have switched to a steel braided style flexible section, perhaps the hardware is easier to attain/manufacture than the bellows style, who knows.
I too sometimes want a very loud sound from time to time but have settled on the center bypass, with carnewal remote switch which lets you control the valves and keep them open or closed.

I'd like to know what these rallye guys have been running-the sound is intoxicating-I already have 2 very loud motorcycles with open pipes(two stroke triple 750 with chambers and stingers ) so valved sides with FVD center might be close to what they have. Does a valved side with center bypass make a difference with valves activated? There was a reenlister in Puerto Rico that tried it (Rick930 I think is his member name, but his videos didn't show enough to make a decision imo-

Rallye:


Carnewal:

http://www.carnewal.com/products/997...Manual-Control

noro78

I am very happy with my RSS center delete. Great quality and the tip design makes the car sound like F1 at 7K rpm range. My only beef is with the way factory valve works under the Sport condition, but it's an easy fix with a remote in cabin switch.. perhaps I'll get around to it this winter while the car is asleep.

bweSteve

Bovien, My wife & I just went through this exact same evaluation with our 997.2 GT3.
reference: https://rennlist.com/forums/997-gt2-...ilter-wet.html

We started out just disconnecting the valve solenoid to keep the valves open 100% of the time, because we both HATED the on/off opening/closing at odd 3k / 4k moments while driving. Horrible vacuum related logic.

Anyway,... at that point, we definitely preferred the full open valves all-the-time sound, BUT there were moments in certain gears, while just cruising down the highway, at certain rpm spots, where drone entered the cabin. Did not like that.

So we moved to the SharkWerks center bypass, and now LOVE IT throughout the range, PLUS were surprised that it actually eliminated the drone at those low rpm cruise moments. We only have a couple hrs in it though, so we're still in "eval" mode, but so far we're happy.

Now, neither of our ears hear a drone, AND we have a much better overall sound.

Our NEXT step is to move to a on/off switch, so that we can use the valves again. I hate the fact that I've eliminated the usefullness of the valves (thinking of neighbors at 6am on weekends when we head out early). So I want them operational again soon (as you do, but for different reasons I guess).

So that's our experience. But now if someone could point me in the direction of the on/off switch mod that converts the valves from using the vacuum solenoid, I need it.
I've seen it referenced, but have no idea who makes it, nor who sells it.
TIA!!!

Oh, Btw, I do indeed have a WOT video clip from BEFORE I did the SW bypass,.. and hope to find a nice sunny day to make the same video again (same place), now that we have it modified. Comparison video.
Coming soon, stay tuned.

=Steve

boostedt0y

Izzone

bweSteve

Thanks Boosted.

Went to the Carnewal product description. http://www.carnewal.com/products/997...Manual-Control
Belgium. $175 Euro / $205 US

The pic showing the parts included in the kit are not clear. Does anyone have the installation instructions? I'd like to read those. Says 10 min install, totally reversible without a trace, and no skills needed (Lol).

Found this morning...
JB911 has a good description of how to plug in the Carnewal system in Post # 6 here...
https://rennlist.com/forums/997-gt2-...s-at-idle.html

Sorry to hyjack your thread Bovien,.. but it sounds like this Carnewal system from Gert would give you the ability to close the valves for your low Db track days.

=Steve

bovien

Thanks a bunch. My "design tek" sounds great as well, but I have a hard time to do a reference as I don't have any other 997.2 gt3's around with swapped center boxes. I have a feeling, that the sound inside the car can be bettered without the rear of the interior resonating resonating at high revs WOT. And its an expensive test to buy a setup home from abroad and finde the issue is more or less the same.

Sweet Steve. I had the same feeling when I installed the x pipe I have now. But after a while, I started to miss the more docile quality sound of the OEM, I switched back. Now I miss the volume below the 4k, and I'm feeling there must a best of both worlds.
In regards to you valve issue, there is the possibility of doing the "laguna seca trick" where you simply bypass the switch in the engine bay and connect two vaccum hoses. Its a 30 sec operation, but that won't allow you to switch from inside the car. It must be quite easy to just add a 12v swich to the wires from the switch itself, but I have never gotten around to actually doing that. I'm guessing it is the same the product mentioned below does at a higher cost.

Gussing you would brake the 95db limit we have at most trackdays here?

zdet

I've had both GMG and Sharkwerks center bypasses on two different 997.1 GT3s. Due to mid-range drone, I ended up removing the GMG and replacing it with the stock center muffler on the first car. The second car had the Sharkwerks bypass installed upon purchase, but I received a stock center muffler with the second car. I planned to remove the Sharkwerks bypass based on my experience with the GMG, but, over a year later, I have (and will) not. There is no noticeable drone with the Sharkwerks unit and the sound is intoxicating. Anecdotally, there seem to be some meaningful variations in center bypass options.

Tom@TPC Racing

Delete pipes fall into two camps: side delete or center delete.
If weight reduction is more important... side delete drops ~40 lbs, center delete drops ~12 lbs.
For reducing heat retention around the area of the ignition coils and valve covers side delete is will do that.
Sound preference is subjective, side delete produce a deeper note, center delete produce a more screamer note, some driver prefer one over the other, personally I think they both sound good in their own way.

Recently my GT3 got rear ended, my car has side deletes and OEM center muffler, the center in this incident took some of the impact to save my engine.