Newbie here with a 2009 4S and Akrapovic exhaust question. Is the Akrapovic cat-back exhaust system worth it over the Fabspeed and Tubi systems? Nearly half the cost but at the end of the day, I want the best HP/flow gain along with the best sound with no drone. I am comparing the complete system replacing all three mufflers. The stock headers/cats will remain Thanks for the help.

 

Couple of things to consider:

1) Horsepower gains will be virtually zero when replacing the stock 997.2 cat back exhaust - so it would be good to go into it with a realistic expectation

2) Everyone has their own concept, expectation, and ultimately opinion of what a "best" sound is. Even if you get sound clips via the internet / YouTube, the quality of what you'll be hearing is not telling.

Making a sizable investment based on others opinions of sound may end up being a very costly dead end for you.

You should seek out other 997.2 owners in your area (via the local PCA chapter perhaps) and ask to see / hear their cars firsthand.

 

Okay, what is the deal with horsepower gain or no horsepower gain ("virtually zero," according to Ironman88 in the above post) with replacing catback exhaust components of the 997.2--that is, mainly, for most of us, centre muffler bypasses? Or does just apply to Akrapovic/Tubi?

Anyone survey the numbers? For example, both Fabspeed and Sharkwerks claim 12hp gain with the centre muffler replacements. If true, that's not too bad, given you also get great sound, especially paired with gundo-style mod.

 

etom, same question for me. I was surprised by that statement. Not sure how a company can advertise the HP increase numbers and not be true. Law suits from hell from that one...

 

This is how I see it. The difference in HP between my -09 C4S and my -11 GTS is 23 or twice the gain from the exhausts mentioned and I have to try really hard to notice the difference. Not noticeable for all practical purposes and those 23 HP came from Porsche's X-51 kit which when sold retailed for around $17,000.

The HP gain may or may not be accurate. The point is.....can you detect a 12 HP gain? As I said above, I'm having a hard time detecting twice that gain.

 

To Sandwedge’s point, use the 10 pounds per horsepower wag. Take a passenger with you and go do some pulls. Kick the passenger out and do the same pulls. If you have the equipment, record data for each of them. See if there’s a notable performance difference. A 130 lb woman would be the hp equivalent of a good full exhaust system upgrade. Your friendly neighbor 250 lb linebacker type would be a Powerkit.

 

Gaining 12 HP at the rear wheels is just gravy.
We do the mod for the sound, not necessarily for a power increase.

As sandwedge points out, a 997 GTS has a 23 HP advantage over the 997.2 S engine- due entirely to the induction system of the X51 Powerkit.

Add in a 12 HP gain from a Sharkwerks center muffler delete and now there is a total 35 HP gain...
(almost 10%- from 385 to 420 in a 3200 LB vehicle.)

An N/A 110.5 HP/LITER engine, with the gains attained solely through better induction and exhaust, is pretty cool.

The stock 997.2 GT3 engine output is 114.5 HP/LITER.

The stock 997.2 GT3 RS is 112.5 HP/LITER.

The X51 costs $17K for 23 HP.
The Sharkwerks costs $1K (plus 2 hour labor to install) for 12 HP.
And killer sound when paired with OEM PSE.

A real no-brainer, IMO.

 

The cat back muffler setups really gain sound and maybe a couple of ponies that you'll never feel. Real exhaust improvements come from using equal length long tube headers so the exhaust pulses sequence properly with less turbulence and from using high flow cats, but even those changes result in very modest gains on a NA car. Don't believe the published numbers as you can make a dyno say anything and no dyno can simulate real world air intake no matter how many fans you blow on the car. The amount of air entering an intake system is completely different at even 40 MPH (not to mention at 100 MPH) than what you can simulate in a stationary situation. If you did a full exhaust, intake, and a tune, you might find 30 HP - might, and most of that gain will be up at high RPM, not where the car is normally driven on the street. The only way to make real power is by forced induction - when you combine intake and exhaust mods with a turbo or supercharger, you get a 100-150 HP difference that you actually can feel, but by the time you've done that, if you take all the money you spend on intake, exhaust, supercharger, etc you're almost at just trading your car and buying a TT, which is a much smarter solution for the average owner. So, buy the exhaust that sounds great to your ears, but buy it for the sound, not for the performance gain.

I have a complete Fabspeed setup with their valved mufflers on my supercharged 997.1 and love it, but the 997.2 is a different animal and makes different sound.

 

Anyone in the community is welcome to stop by HQ with a stock 997.2 and we can throw it on the dyno! The results are all very real.

I also strongly agree with Petza, If you're looking for a night/day change you're better off selling your car and buying a Turbo. Gains on N/A cars ware always a struggle, end of the day you may not feel the 12WHP increase but its there.

 

So this is all interesting, and thanks for everyone's chirping-in. So, you can't feel 12hp (though, in a way, you actually hear it). At what magic point is hp actually "felt"? To use the night/day metaphor, is there some kind of twilight? dusk?

For those of us who have the 385hp S models, we of course want to reach The Magic 400hp level, just for the sake of bragging rights, right? So with the addition of 12hp via a centre replacement exhaust, we get 397hp. Now, how can we find that extra 3 hp to get to 400hp? All 3hp advice welcome; also, we do understand that some colours may be faster than others.

 

fill your tires with Helium and don't turn on your A/C = 3 whp.

 

Porsche decals on the doors must add a solid 15bhp a side.

On a side note I have 997.2 C2 with an xpipe. Very happy with the sound, such a difference over stock and sounds really throaty. Love it.

It doesn't drone on when you are driving normally as well which is a must.

 

If you haven't, check out the latest episode of PCA's Tech Tactics Live YouTube channel. All three indy Porsche shops recommended staying with factory parts. They pointed out that proper back pressure is vital to the factory tune. I would not take after market manufacturers word for more hp. You may gain a better sound, but most of the time you will lose power.

 

I know in the 991 rs cars akropovic is the top of the line. I'm sure it'll be nothing short of fantastic in a 997. If money was no option I'd love to have one. I just did the sharkwerks bypass, for the money it's almost impossible to beat sound wise. I didn't care much about the hp because you'd never feel or notice it anyway. The s model puts down 385 hp from a 3.8 liter engine. That's incredible when you think about it, porsche didn't hold much back with .2 engines. Plus when people do rebuilds they always up the displacement to get more power, it's about all you can do besides forced induction.

 

As a completely satisfied customer for my Sharkwerks bypass, I would take any manufacturers HP claims with a grain of salt. After installing mine and loving the glorious sounds it makes, I could tell no difference in how it pulls in my GTS.

Sandwedge is on the right track. A powerkit includes modified cylinder heads, a valved intake manifold, a factory tune and higher redline. That gets you 23 horsepower.

But....but, changing a muffler gets you halfway there? I don't believe any dyno claims unless it's a 3rd party, and nobody has those on their websites.

Porsche has done a remarkable job squeezing a ton of hp out of a liter of displacement. I doubt they would have left hp on the table by neglecting a simple exhaust modification.