981 GT4/Spyder Header/GT3 Muffler Exhaust System


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Add Power and great sound and experience your Porsche’s true capabilities with the Dundon Power...

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Our Street Header Package with Dundon GT4 Race Headers back by 200 CPSI (cell per square inch) Catalysts, and Lifetime (or your provided GT3) Muffler Power Package delivers the power and sound you want while keep catalysts! 


Dundon 981 Cayman GT4/Boxster Spyder Street Header Power Package provide substantial gains in torque and horsepower throughout the rev range.  They are a street system.  All Dundon headers are made with 321SS, the advantages of this are numerous and include, better fitment, higher heat tolerance, superior resistance to exhaust gas corrosion and a lifetime structural warranty to the original purchaser. 


The headers attach to the factory PSE muffler and are quiet with no drone at cruise, but put your foot down and they're all kinds of flat six glory.


Dundon Headers are specifically designed for each vehicle and engine.  Unlike our competition that uses a one size fits all, we tailor each system to the unique needs of each engine.


Dyno showing Stock GT4 vs Dundon GT4/Spyder Street Header Kit, no tune.

stock tune chart

Gains Over Stock.

3600 RPM: +42 wtq

5000 RPM: +36 wtq, +34whp

5800 RPM: +15 wtq, +16whp

6500 RPM: +28whp

7000 RPM: +30whp

7500 RPM: +41whp


Our dyno read the stock car at 330.8 whp at 7400, Porsche rates the car at 385bhp at 7400, this is 14.1% loss with our Dynapack 4000 hub dyno running the car in Rolling Road mode using the factory PIWIS tools.

Dundon Street Header equipped GT4 is now at: 426BHP


GT4 Tunnel video



Dundon 991 GT3 Stage 2 chasing GT4 Stage 2



The GT3 Muffler adapter is used in our popular D4 (stage 4) GT4 power kit, and fits all 981 chassis cars!


2.5" 321 Stainless over axle pipes

2.5" Valves

GT3 Muffler Bracket

GT3 Muffler Straps

Optional 200 CPSI cats

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