ApexBuilt® BMW F97 X3M & F98 X4M GESI High-Flow Catted Downpipes (S58, 2021+)

From $2,999.99
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ApexBuilt® F9X X3M/X4M GESI HFC Downpipes offer...

• No check engine light on factory-tuned vehicles.

• 49 state emissions legal*

• Industry-leading build quality.

• Perfect fitment, guaranteed.

• Drastically improved throttle response, quicker turbo spool, and an aggressive exhaust note versus OEM.

• Estimated gains of 20-25+ wheel horsepower and 40-50+ TQ when installed on a vehicle that is not tuned.

• Estimated gains of 45+ HP and 60+ TQ over stock power levels when paired with an aftermarket ECU tune.

• TIG-welded T304 stainless steel construction, assembled by hand in Naples FL.

EPA approved GESI GEN2 UHO metal-core 400cpsi 4.5" cats, rated for 500-800hp applications & road legal in 49 states. 

• Lifetime warranty.


These downpipes will not be sold or shipped to the state of California. GESI 300cpsi cats are EPA approved, but not CARB approved – meaning they're street legal in all 49 states EXCEPT the state of California. 

Read more about GESI cats: https://gsportbygesi.com/high-performance-catalytic-converters/g-sport-catalytic-converter-technology/


• 18328053345 (Cyl. 1-3)
• 18328053346 (Cyl 4-6)

Fitment supported for the following vehicles:

BMW X3 M F97 (2019+)
BMW X4 M F98 (2019+)