Arrow #4 is indicating the final exit.

"I'm not sure if you have seen this a dyno chart for a hacked muffler. I'm just curious what they exactly did to it, since it's quite an improvement, especially the torque.

-- peer "

The dyno chart shows the difference between a stock oem muffler and a "Sporttech" muffler. I don't think the sporttech is a hacked oem muffler.

"No. They do interact in the middle of the muffler. That first pic is misleading. The left and right inlets connect in the middle; it is straight though from end to end. perforations along that length determine where the gas spills out into which chamber.

boxsterz"

The inlet pipes on my 1998 muffler do not go through from end to end. When inserting a dowel into one side or the other there is an obstruction about 18 inches into the muffler.
You may be correct about the perforations determining which chambers the gasses flow into. There is a difference between the two pictures that were posted. I don't if the first one is from an older muffler.
From the picture Toolpants posted it appears that the perforations would cause the majority of the gasses to flow as I indicated in my ealier post.

John

That's interesting. Guess it's fair to say the 2.5 mufflers are different.

szentej wrote:
> The dyno chart shows the difference between a stock oem muffler and
> a "Sporttech" muffler. I don't think the sporttech is a hacked oem muffler.

Actually, the so-called sporttech muffler is a hacked oem muffler.

-- peer

I stand corrected. The Sporttech muffler is a hacked muffler. You send them your muffler, they open it up, take out the guts, add bypass pipes (from the inlet to the tail pipe) and reseal. And you get to pay them $500 for parts and labor.
The above option is cheaper than installing a Porsch Sport Exhaust (big $$$$). The Porsche Sport Exhaust utilizes a bypass system that is controlled by a switch and/or speed sensor. But even Porsche does not claim any significant power gains with this mod.
Or you can go to PPBB dot COM and search for "Pedro Sport Exhaust" to see how to have bypass pipes installed on you muffler at a much reduced price.

John

The difference is that the Pedro Exhaust (and the Porsche Sport Exhaust) don't claim any power gains -- while the Stpotech hack does. Hence, I'm curious what the Sportech guys do to the muffler that supposedly will increase its power (especially the torque).

-- peer

Try here. http://www.boxsterspecracing.whsites.net/phpBB2/

I started Boxstiring 8 years ago. I have a vague recolletion of the Korda muffler and almost no recollection of Sportech.

I do remember there was one company that cut open a muffler, and welded it back up. Might have been Fabspeed.

If it was cut open I called it a Frankenstein muffler.

At our work on cars days I heard a Frankenstein muffler, and it had a rattle inside.

I do not usually trust dyno graphs.

I took this picture of the spec class at Laguna Seca. They are required to run with the stock manifolds, but after that it is free.

Some of the cars had dual aftermarket mufflers. The tips were crimped to increase back pressure, or to increase torque.

Funny how that works in reality.

^
i like that, how there is no license plate section.

Sporttech muffler claims less than $50 per horse power of improvement and less than $50 per foot pounds of torque.
I've got a bridge in New York that I have for sale too. Just call 1-800-Got-tcha. :dance:

The outlet pipes are plumbed to the two outer chambers. Enlarging the holes in the inlet pipes at that point would allow more direct flow from the inlet pipes to the outlet pipes. I believe some people do this without cutting the muffler apart by grinding away with a dremel attachment down the bore of the inlet.