Why do you guys replace the exhaust system? I'm not judging, I just want to know. Is it because the turbo exhaust sounds disappointing from the factory compared to a NA porsche engine?

 

For me, I like the engine sound much more. I have an inconel Kline that I got from Sam on both my cars and it just has a much nicer tone than stock. Oddly enough, the Kline actually has less resonance/drone at steady throttle than the stock exhaust.

To specifically answer your question:
1. The sound is much more appealing than stock to me.
2. There is a substantial weight savings
3. Less restrictive than stock creates an engine performance gain.

 

Two reasons:

First, the stock exhaust sound like a vacuum cleaner. The Aftermarket exhausts I have bought make the car sound great.

Second the stock exhaust and stock cats are so restrictive that you cannot get a major power game from a tune in the car with them on. Tuners can only increase the power very slightly with the stock exhaust and stock cats on. You must get either free flow cats or catless for big power gains.

 

Performance and sound.

 

Have the same system and headers. The car has been transformed with the Kline exhaust for the better. The only weak point to this car for me was the exhaust so the change made sense. I went with high flow cats and have had no issues, no CEL, and dealing with Sam made it very easy!

 

I didn't do cats, but I'm going to have them installed just for the minor exhaust smell at traffic lights. It's not even bad, but for the .2 I really don't plan to modify it much so I want it a little more civilized.

 

Thanks! I was told by the dealer that the porsche "sports exhaust" is superficial meaning the cool sound doesn't enhance performance in any way.

It's good to know you get a cooler sound, but also performance and weight savings.

Why is the CAT so restrictive? Is it for environmental clean air standards? Or is there some other reason?

How different does aftermarket sound? One of the threads here wanted to know which aftermarket exhaust it was, and the exhaust had a ton of backfiring when it popped/crackle when he let off the gas. Other than the sparks and backfiring when deaccelerating what sound would I hear when just idling or accelerating?

 

I also have the .2 and it's a cab. After talking it over with Sam went with the 100 cell. No issues/smells and great sound!

 

Here is my car with the FVD headers, FVD exhaust and 200 cell cats. The cost of that setup is around $6k I think. The headers failed and so I replaced them with the stock manifold but put in cat bypass pipes so the car is even louder and meaner than this now. It's currently in the shop waiting to be put back together with the TIAL turbos and I have a Kline Inconel header set on the way. When I get it back it should be much faster and sound even better. I will try to make a new driveby when it's all put back together.

 

Good video. Sums it up pretty good. I'm glad you took the time to make that video for all of us because I'd never get to hear that type of mod in real life. Now I have a better understanding why so many exhaust threads pop up here too.

Even though it sounds substantially better I probably won't do that mod because I like it to sound tame, except when I don't lol.

 

An interesting aspect is that the car is pretty much as tame as stock UNLESS you're getting on it. I'd highly recommend finding someone local with a setup that you can hear. Or fly to L.A. and come for a ride!

I'm sure Sam from By Design can offer you some advice on how to get a listen in real. I can tell you that the car is in no way obnoxious with the full exhaust. I live in a canyon in L.A. and I could not terrorize my neighbors so I had to make sure my cars are not crazy loud.

 

Most people do it for 2 reasons, performance and sound. The two sort of go hand in hand. In order to design an exhaust for better performance, the goal is to remove restrictions and free the flow of exhaust from the turbochargers all the way out to the exit. By doing this, you relieve backpressure on the turbos which allows them to spool faster and not generate as much heat. On the 911 Turbo the factory cats are 700 cell, which basically means they are a much more densely packed material which is, in turn, more restrictive. The muffler is also designed to keep sound at a minimum, which also adds some more restriction.

Most aftermarket exhausts offer varying degrees of sound and flow. Some have 200 cell cats, some have 100 cell cats, and some have cat-delete pipes (the freest flow). Most will also use a much freer flowing muffler as well. Regardless of which option you choose, you'll most definitely notice improvement in sound and performance by doing just an exhaust alone. But adding a software tune will help TONS as well.

The image below shows a pretty good example of a stock cat vs a free flowing cat. (not necessarily for Porsche and I'm not sure what cell count they are, but it's a good illustration.) On the left you have an aftermarket cat, and on the right a stock one.

Hope that helps.

 

DO all custom exhausts have a higher pitched high performance motorcycle like a ferrari sound? Or do some of them sound deeper?
Is the higher pitch typically more favorable?

 

That picture does help. I was thinking how much restriction could there possible be as wide as those pipes get with 4 giant exhaust tips? I didn't know it was packed with a filter.

 

Unfortunately you'll never be able to duplicate that Ferrari type of sound with a 911 Turbo. The turbochargers themselves change the sound of the engine, since they're basically a part of the exhaust system. But you can definitely improve the sound tremendously! Most 991's with aftermarket exhausts will have a deeper more aggressive sound.

Yup...catalytic converters can be VERY restrictive. Removing them or replacing with a high flow cat is a key component to any 911 turbo performance program and should be one of, if not THE, first steps you take if performance and sound are goals.