GMG Racing WC-Sport Headers

The GMG Porsche 991 Turbo exhaust manifold system is handcrafted from the highest grade 321 stainless steel and features equal length tubing and large 3 into 1 merge collectors.

The GMG system is designed to reduce exhaust back pressure and complements the 991 Turbo's capabilities with improved throttle response and an increase in power and torque output. Utilizing equal length tubing and large 3 into 1 merge collectors, smoother flow of exhaust gases is achieved.

GMG chose 321 stainless steel to build the 991 Turbo headers due its improved heat management properties over 304 stainless steel. For many high performance turbo applications, exhaust gas temperatures (EGT) can exceed 1400° F which is beyond the working temperatures of mild and 304 stainless steel. Because of its excellent resistance to fatigue and cracking at elevated temperatures, 321 stainless steel tubing is one of the most desirable materials for exhaust systems.

Stabilized with titanium, 321 is an excellent choice for most turbo applications due to the increased material strength at high temperatures. To prevent premature cracking or warping, the GMG manifolds utilize laser cut flanges and each side of the turbo flanges are TIG welded. Proper welding technique is very critical for turbo headers due to the high stresses they see when in use. To reduce heat and to direct more exhaust energy to the turbochargers, thicker stainless tubing is used versus standard thin wall stainless. 321 stainless conducts less heat than mild steel, helping to reduce heat and to direct more exhaust energy to the turbos.

The GMG Porsche 991 Turbo exhaust manifold system is designed to work with the factory turbochargers as a bolt-on replacement. It will fit both 991.1 and 991.2 generations.

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