Back Presure Vs Weight Loss

thirteeneast · Oct 2, 2010

I just cant make up my mind.

Our mufflers are Heavy. Very heavy I would guess around 50kg.

But what's best?

Lose 50kg or lose a bit of back pressure by only having bypass pipes.

I reckon lose the weight. But can it throw a fault

watlina · Oct 3, 2010

Have you actually heard a 996 on bypass pipes?

Those 50kg mufflers are not just there to provide back pressure the clue is in the name.

Bypass pipes are a complete waste of time. People who think "I know I'll save a load of money on a performance exhaust and just fit bypass pipes" soon discover after driving about 5 miles that the noise is just unbearable. And don't even think about passing trackday noise limits with them. If you want a set of bypass pipes have a look on eBay as there's normally a set from someone who's regretted getting them.

There are loads of good performance exhausts about that will save a few kgs but the weight saving or in fact the perhaps slight increase in power you might get is not worth it. The main reason to change anything with the already decent exhaust is just to make it sound better without going too far.

steveoz32 · Oct 3, 2010

I don't like the sound of the bypass pipes at all:

http://www.youtube.com/watch?v=leuxQ0EpNOw

It sounds like someone starting a peugeot 106 with the manifold blowing and the down pipe removed. But then that's just me - not a fan of loud exhausts.

I like the sound of the stock setup, nice and smooth

unclewinks · Oct 3, 2010

Terrible sound, NOISE POLLUTION,If you want to save weight try changing your brakes to pccb,much lighter

thirteeneast · Oct 3, 2010

I understand that bypass pipes are noisy. as there's a Muffler missing (clue in the name). And that's why PSE cut out is there.
But its main purpose is to fall within manufacturers guide lines.
I am purely stating that all I ever here is opinions and would like to know some real performance results.
Not "its noisy"
"obviously its going to be loud"

unclewinks · Oct 3, 2010

Performance exhausts don't give you that much in performance figures unless you start changing airflow,the x51 upgrade on our car only gives 25bhp extra
The upgrade is quite extensive for such little power increase
Exhaust(pse)
camshafts
Clutch
Cam followers
sump
Intakes
Gearbox bearings
So as you can see a lot of changes for not a lot
I have also had a revo re-map which doesn't really boost bhp or torque by a great deal but it makes the car more responsive and smoother
If you read Tom O'Kelly's write-up on the modifications he has done to his 997 (the beast) you will see how he has done and the performance figures,quite impressive
Paul

thirteeneast · Oct 3, 2010

Many thanks.

watlina · Oct 3, 2010

ORIGINAL: steveoz32
I don't like the sound of the bypass pipes at all:
I like the sound of the stock setup, nice and smooth

The standard setup is fine for most people but there is room for a bit more noise. The standard boxes are designed to meet noise regulations around the world so are on the quite side for a sports cars.

One of the ways to a better sound is a small bypass pipe on the standard exhausts. This is effectively what Porsche do with their Switchable Sports Exhaust but they also add a pneumatic control valve to switch the bypass in and out. Modded exhausts with a permanent bypass are available on eBay for about £500 http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=370260199138

The genuine Porsche ones often come up on eBay as well
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180565647177
Without the wiring and vacuum pipework they are in loud mode all the time, which is how mine are ;-)

watlina · Oct 3, 2010

ORIGINAL: thirteeneast

I understand that bypass pipes are noisy. as there's a Muffler missing (clue in the name). And that's why PSE cut out is there.
But its main purpose is to fall within manufacturers guide lines.
I am purely stating that all I ever here is opinions and would like to know some real performance results.
Not "its noisy"
"obviously its going to be loud"

As others have said if all you want is more power then really don't bother. The costs for more real power on the standard M96 engine are hideous. The best option is to just buy the faster version in the first place. Early GT3 are not bad money but the real performance bargain is the Turbo there's no way you'll ever get the M96 near to the standard 420bhp of a Turbo for the cost a Turbo is over a standard Carrera and then with the Turbo it's pretty easy to take to 500bhp if your still feeling inadequate.