924Board.org

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Two independent experienced, competent, sources have used the 944 exhaust modification/upgrade on their cars, and on customer cars, and wrote that it is good for 8-10 horsepower.

One is Don in Texas. I don't remember his last name. Don is a known 924 racer, with a shop that has a good reputation. He, and his shop, build, race, and maintain, racing and street Porsches. His word is good enough for me.

I don't remember who the other guy was at the time, but he 2nded the same modification/upgrade and said that he was getting the same result.

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

The 944 downpipe has the cat welded to it. The 944 downpipe will not bolt directly to the 924 exhaust manifold.

To use the 944 downpipe need to hang the 944 final muffler, then attach the 944 downpipe assembly to figure out exactly where to cut the downpipe so it can be attached to the 924 downpipe at the existing rear flange of the 924 downpipe.

The 944 downpip/collector will not bolt directly onto the 924 exhaust manifold. If you want to use more of the 944 collector/downpipe, you would probably need to make a could of cuts and welds to the pipe. the 944 collects ends at a flange that is lower down than the 924 dowpipe. So you would have to add length to the 944 collector to bring it up to the 924 height of the 924 exhaust manifold. You might also need to play with the length of the 944 collector/cat assembly to make the 944 collector (with the added extension to meet the 924 exhaust manifold) meet the 944 final muffler assembly in the stock location).

924RACR · Posted: Thu Apr 12, 2007 10:11 pm Post subject:

You'd be thinking of Don Istook. I do trust his input, and bug him from time to time...

One day I do hope to try out the Stahl header, but had to replace my header last year and didn't have $500 or so to fork out - so I went with another MSDS header.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Yep, Don Istook.

I was just pondering, trying to remember his last name, when it came to me. I dropped back in here to fill in his last name, and you beat me to it.

NBRettie18 · Posted: Fri Apr 13, 2007 4:22 pm Post subject:

i want to get a new exhaust system for my 87 924S. what kind can i get? ive looked around and cant really find any.
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1987 924S - MO30 30/19 - Yellows all around

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

Don Istook would certainly be a reputable source. Still, he messed with these cars a LONG time ago. Dynos were not all that common then. So I wonder if he really did JUST an exhaust change and then dyno'd a car? And our recollection of the details may be faulty after all that time. So I wonder if other mods weren't done at the same time? 8-10hp is a lot of improvement.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82

tyfighter123 · Joined: 19 Jan 2010 Posts: 551 Location: Colorado

So out of the options out there bursch, stahl, etc what is everyone using?
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Porsche 924 1977 N/A
Mustang GT/CS 2007
Porsche 924S 1987 (parts car)(cut up and recycled)
Porsche 911S 1976
Porsche 931 1980
Porsche 931 1980 (parts car)