Stylemobile

Well I've read most of the multitude of posts regarding exhaust modification: X-pipe, Y-pipe, Chinese letter for insane American-pipe, take this or that off, etc. and notice a pattern among many 928 owners that baffles (pun intended) me....
To me the deadliest things in this world that are impressive for their abilities are understated and stealth. Examples: A panther, cobra, scorpion, black widow spider, a samurai, a sniper with a silencer, etc,..
What is accomplished by giving as much attention to making our cars louder as to being more powerful? Shouldn't the goal be to to keep it as quiet as possible while delivering the most power to the rear wheels? Wouldn't you rather have a group of people at an outdoor cafe turn their heads toward you with smiles admiration rather than cringe and wince in pain or disgust?

I will admit that i appreciate a fine sounding 'note' to any serious machine but there is a threshold beyond which you are only terrorizing innocent victims. A loud car also means you can't hear and understand what is going on around you very well. One of these days, some idiot on a Harley with straight pipes with a "loud pipes save lives" sticker on his helmet will loose his life because he couldn't hear the ambulance or fire truck with sirens screaming coming through a road intersection.

Will someone with the wisdom to respect the environment please advise me on how to increase my 928's power while at the same time permitting me to enjoy the cabin so beautifully designed by Porsche to keep sound away from my ears?
I should not HAVE to turn up the music (or even on at all) to drown out the mechanical noise of my fine car.

I know that i have now set myself up here for the heavy humor blasts but someone please advise me with sincerity. After all, this site is here for that main purpose (as much as i have enjoyed and laughed heartily at some of the rants and battles here).

All the Best,

Allen in Allentown, PA

"Your right to swing your fists around end where someone else's nose begins."
- Benjamin Franklin Howells Jr.

shmark

Wuss.



Actually I know what you mean. On my last 928 I had a test pipe on and off the car before settling on having it off. It just seemed right to have a quiet GT. Well I've grown down since them. I've had a bunch of loud cars ranging from an Rx7 with a header-back Racing Beat exhaust (sounded fantastic), a modified 951 with a full Fabspeed setup (also incredible, shook the house when I started it) and the loudest was a 914 with a built 2.0l, Weber header and a straight pipe. Ok maybe it was too loud, but wow.

I'm also embarking on a quest to improve the engine response and power and the first step is exhaust. I don't want something ridiculous (like that 914) since this is a very nice street GT, but I want it to breathe better and have a little authority. So my goal is freeing things up while getting a nice muscular sound that only opens up when I get on it. At the recent dyno day, most of the cars had exhaust mods of some kind and for the most part, they were very mellow in street driving. My bone-stock car was the quietest by far, hardly knew it was running on the dyno. Going to fix that.

RKD in OKC

I can understand your stealth quest a bit as my 944 Turbo with 4 inch exhaust and FlowMaster muffler attracted a police cruiser from 3 blocks away.

However, you sir, must have never gotten goose bumps and had the air stand up on the back of your neck from the melodious sounds as you rev up through the gears in a 90 GT with stock exhaust with the addition of a simple RMB! My Stock exhaust GTS had zero exhaust sound except for the low quiet rumble idling. I added the RMB because I couldn't even hear the exhaust in a tunnel with the windows down, just the motor itself screaming.

That being said, if you want to extract maximum power with the lest volume the 928 has an advantage over most because with the baffles and cats there is space for yes, more mufflers. I dare say I think the optimum silent power solution would be headers, x-pipe, mufflers in place of cats, mufflers in place of baffles, and the stock rear muffler. As long as those mufflers are the flow thru type with no restriction ie. similar to the stock resonators.

From my experience with a 944 Turbo with 4 inch exhaust, Magnaflow brand mufflers are the least restriction with the most sound removal. Putting a second muffler in place of the cat on a 944 turbo further reduced the volume by 5 db without measurably reducing the power compared to a cat bypass. The 4 inch exhaust with the same brand of muffler was 10 db louder than a 3 inch exhaust. Of course on a turbo car, the turbo itself reduces the sound output some, but it is still in the 83 to 93 db range (moderate to loud, 93 is the legal limit here in OKC).

Ketchmi

Just for information sake, when I re-designed Louie's crossover into the Motorsport crossover sound had nothing to do with it. It was all about the horsepower baby! I tried to extract every single HP I could get out of the system regardless of the noise it produced. That can be tailored by mid mufflers, rear mufflers and personal preference varies so much there is no "right" sound. I felt that losing horsepower to make it more stealthy was not worth the trade off.

BTW, camshaft profile does have a lot to do with the note of the exhaust and GT cams/timing do produce a completely different song than S4 cams with exactly the same exhaust components.

RKD in OKC

Dang it, now I want GT cams in my GTS for the song, and I bet that is just what it would cost

Landseer

Do you need to run catalytic convertors on this car, assumeably registered in Pennsylvania?

dprantl

I find my GT has the perfect sound level for me with the motorsports X-pipe and metal matrix cats, then stock GT exhaust back. And it passes emissions with flying colors. Judge for yourselves:

http://www.callouie.com/porsche/Atl_dyno_day/dyno3.wmv

Dan
'91 928GT S/C 475hp/460lb.ft

Stylemobile

Only a visual inspection of the emissions system is required for my age car and I know a mechanic or two who have some 'trouble seeing'.

Please continue with your advice with this new information.

Allen in Allentown, PA

Stylemobile

Off Topic: OK. Feel a little sheepish regarding the 'right to swing fists' quote at the bottom of my topic posting. I heard it from my Father when i was very young and attributed this to him when it was , in fact, Oliver Wendell Holmes. Back to History class for me...

ROG100

On the earlier cars 78 to 84 I use the Y pipe with a Borla or 928 Int cat back system and the sound does not change from the stock setup just a change in tone to a V8 rumble.
On my GTS with X Pipe, cats, stock muffler and RMB the same - no extra noise just a change in tone.
I like stealth.
Roger

Charley B

Shouldn't the goal be to produce any combination of sound and power your taste and wallet dictate? That is unless Allen is paying for your car, in which case it might be a little quieter...........................just kidding Allen.

PorKen

I like having some muffling, if only to cover the sound of the automatic gear changes. It spoils the sporty image.

Landseer

Now that's an inventive practical definition of "stealth".

Leslie 928 S2

Hi Allen!

In my opinion, the 84 Euro stock twin-pipe exhaust is the best of both worlds, when what you want is quiet and more power. You can go by people without being noticed for your sound. You can hear it's a V8, but it's not offensively loud.

That being said, I like the louder sounding exhausts. And yes, I still love cranking the music when I drive. Not head banger music, usually...I'm more of a country girl, myself...don't ask me how that happened, being born and bred a Jersey girl. lol. Anyway...I kinda never grew up in that respect, and I hope I never do. Well, except in the fact that, being older, I've learned the wisdom of turning it down in heavy traffic or unfamiliar areas, so I can hear traffic and think clearly.

Also, the Harley guys may be onto something there, with their "loud pipes save lives" slogan. There aren't that many of these cars produced, relatively speaking, in proportion to the rest of the automobile industry, and then deduct from that number however many have gone to that great junkyard in the sky, and then deduct from that number however many more haven't made it to the junkyard yet, but still languish in barns, and garages, and under car covers in people's driveways.

We all, for the most part, have a large chunk of change invested in these cars...just for the privilege of driving them and enjoying them in their powerful, stealthy, luxurious, aggravating, frustrating, yet speedy kind of way... Some of which owners have, perhaps, a much larger percentage of income into their cars than others......the younger ones come to mind.

Besides, I can't tell you how many close calls we've had, driving completely defensively, in heavy traffic, or even just from the dumbass at the school who keeps almost driving up onto our front hood trying to park, and once actually scratched our car before stopping, because he "can't see the car, it's so low to the ground."

When I want to pass people on the highway and I'm not sure they have seen me, I like to know that when I put my foot to the floor, people know I'm coming and are less likely to cut in front of me inadvertently.

However, when I'm just cruising along at lower rpms, you don't even notice I'm there.

So that's my philosophy in a nutshell.

Btw, Kevin and I can't wait to meet you at the gtg in October.

Stylemobile

Leslie,

I will drive into New Jersey with little audible fanfare. . . .

All Best,

Allen