SLN BMW B58 Super 5” 200 CEL Sports Cat Downpipe CERAMIC COATED

The SLN Performance 5” Ceramic Coated Sports Cat Downpipe is a high-flow upgrade engineered for the Gen 1 BMW B58 engine. Featuring an oversized 5” primary section tapering to a 4” flex section — the largest combination available for the B58 — it provides exceptional flow while retaining a 200-cell high-quality catalyst. Ideal for drivers wanting big power gains without committing to a full decat.

Fitment: B58 Gen 1 Models – M140i, M240i, 340i, 440i

Key Features

Massive 5” to 4” High-Flow Design

– The largest downpipe design available for Gen 1 B58
– Maximum flow with zero bottlenecks
– Delivers power comparable to a decat with reduced emissions impact

200-Cell Performance Catalyst

– High-quality sport cat
– Improves exhaust flow while reducing fumes
– MOT-unsuitable but cleaner than decat alternatives

Ceramic Thermal Coating

– Reduces heat soak
– Helps keep intake temps lower on the B58
– Protects surrounding components

SS304 Stainless Construction

– Aircraft-grade stainless steel
– TIG-welded for durability
– Designed for tuned engines

Benefits

The SLN 5” sports cat is designed for maximum performance without the full harshness of a decat. Expect smoother power delivery, strong mid-range torque, reduced backpressure and a deeper, more refined exhaust sound.

Fitment

Suitable for the following B58 Gen 1 models:

– BMW F20/F21 M140i (2016+)
– BMW F22/F23 M240i (2016+)
– BMW F30 340i (2016+)
– BMW F32 440i (2016+)

Installation Notes

– Not MOT compliant
– ECU tuning recommended
– Professional installation advised

About SLN Performance

SLN Performance specialises in premium exhaust components engineered for strength, flow and heat resistance. Their products are widely used across tuned B58 builds for their reliability and performance advantages.