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Dundon 981 GT4 Race Headers provide substantial gains in torque and horsepower throughout the rev range. They are a race system so are for track or off-road use.


Race Headers are for Non USA or racing vehicles in the US. 


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 Race Headers.

stock tune

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 Race Header equipped GT4 is now at: 426BHP

GT4 Tunnel video


Dundon 991 GT3 Stage 2 chasing GT4 Stage 2