Dundon Motorsports Headers and Exhaust System for the Porsche 991 GT3 RS

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Here is the large metallic cell, free-flowing cat brick. With the cats, there is surprisingly no loss in top end horsepower.

Next is the diverter valve, side muffler delete assembly. In stock form, there are two side mufflers located on top of the cats up into the quarter panel.

In normal operation, the exhaust gasses go through these side mufflers then through a baffled section the main muffler. When the sport mode button is pushed, valves open and allow the exhaust gasses to bypass the side mufflers and go straight to a lightly baffled and larger internal diameter section of the main muffler. This is louder and makes more power.

The Dundon Motorsports parts eliminate the side mufflers and divert the exhaust directly through the more baffled part of the main muffler. When the sport button is pushed, the valves open and allow the exhaust to flow through the larger diameter and almost a straight pipe section of the Dundon muffler.

By getting rid of the side mufflers, the Dundon Motorsports Exhaust system saves over 30 lbs over stock. We will weigh everything to find out exactly how much. Since Porsche spent so much money to pare weight from the RS, this is a significant and relatively inexpensive way to bleed off some more weight.

 

The side muffler deletes are well made from 331 stainless and have a pair of vacuum controlled diverter valves.

The valves hook up to the stock system, so the sport button will still work. As you can see, the sport exhaust path is way larger in diameter, which will make it a lot freer flowing. The sport button will make significantly more power and be quite a bit louder than stock. The stock RS is already pretty loud in sport mode.

The Dundon Motorpsorts muffler is tig welded from thin wall 321 stainless and is designed not to crack or break.

The stock Porsche muffler is an exotic super light piece made out of titanium. However, it is very prone to cracking, especially when being track driven. Some people crack the muffler in as little as 40 minutes of track use!

A lot of this is because the stock muffler is roll formed and pressed together so the internal baffling does nothing to support the thin titanium case. The Dundon muffler is made of stronger thinwall 321 stainless and is fully tig welded inside and out, so the entire muffler is well supported.

All the welding stiffens the muffler and makes it less buzzy and prone to resonance, so even though it is lightly baffled with little backpressure, it is surprisingly quiet with that consideration.

 

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