The X-Pipe debate is a touchy one. But is does many things when applied correctly. Angle of the dangle matters! Two got it right and that's why people LOVE them and they don't drone. FYI the Kline can be configured with several cat set ups. IMO all the systems mentioned are great ones and do things a bit differently.

 

I for one absolutely love my GMG. Adam, I'm also happy to meet up for you to drive mine and hear it for yourself.

To the OP, if you are trying to illuminate the drone you have with your stock exhaust, I would stay away from any aftermarket solution. Even though I don't consider my GMG race exhaust to drone, especially compared to my Ferrari 458, it is definitely louder at cruise than the car was stock. The only way to solve that problem is with a value controlled system. I know they exist for the 991 TTS, but have not personally heard one. I had that kind of control on my 458 and love it. Quiet as a mouse with the valves closed, loud and aggressive with the valves open. ��

 

That's what the Turbo has, and with the Kline work perfect... Just push sport plus and the sounds go up, keep in normal mode and have zero drone and quieter like stock

 

I find this subject interesting. I noticed no difference in volume or tone of my exhaust under normal driving conditions in any of the setting including Sport Plus. The only real difference I notice is at Idle. This was true when the car was stock and modified.

What about everyone else? You guys hear a real difference in the different settings while cruising?

In my M5 and 458, I could open and close the valves by flipping a switch, and the sound difference was drastic. As an example, I would never cruise the freeways with my valves open, unless I wanted a headache.

 

The fuel mapping is different in sports and sports plus than in normal. As a result when you let off the gas when the headers are hot in the engine is at high revs the car especially with catless exhaust lets out a huge bang and sometimes shoot flames in sports and sports plus that it doesn't really do much on normal.

 

Hey Arnie do we have any aftermarket valved exhaust options for the 991 TT?

 

Sorry for the delay I am out of town on vacation and have poor service.

Please feel free to reach out to me if you need anything at all day or night.

We do have updated calibrations to do away with the oscillation in boost pressure. If you update the AP they are already on there.

Let me know I will be around all night if you have questions shoot me an email and I will be sure to help you out.

mitch.mckee@cobbtuning.com

-Mitch

 

Thanks for checking Sam told me about the update and walked me thru what to to do. Got that done in less than an hour and the car runs perfect now!

 

So, if I understand correctly I can eliminate the drone with aftermarket exhaust but I will then at 70-80 have a louder exhaust (compared to stock). If that's the case I would only trade the drone for a louder exhaust which to me defeats my purpose. I would like it to be as quite as possible while traveling 70-90mph. The drone or louder exhaust would be of equal annoyance so no need in spending 3-5k to trade one noise for another!

 

You definitely won't be quieter with an aftermarket exhaust unless you can find a valved one. I had some success by disconnecting the Symposer to make things a bit less noisy, and it was a very simple and free fix.

 

Only one way to find out! SamboTT Guarantee. The Kline 2.5 Will not disappoint at all in any situation. My word on it!

Steve you shouldn't drive your car with something you don't enjoy on it. Give me a call and I'll make something work nice for you...Real nice

 

I know...and I will in the next little while Sam. Thanks!

 

Sam sure does make it hard on all of us!😂

 

Someone has a controlled valve system, but I never had a chance to hear it. After I drove and heard the GMG system, I wasn't concerned about the volume. It's very subdued until you stick your foot in it, which is just what I was looking for. The 458 was very loud when the valves were open, which I loved, just not full time. Concequently the manual switch allowing me totally control.

 

Adam,
techart has a valve control system, you could probably get a brick of gold for about what it would cost..