If you've already replaced the factory airbox of your E46 M3 for a cold air intake kit, the stock rubber intake elbow (which connects the mass air sensor / HFM to the intake manifold) is now your enemy. The stock S54 part has accordian-like grooves on both the inlet and outlet side, which slows down air flow. It's no wonder you don't see this type of restrictive setup on the E46 M3 CSL!

The Samco silicone intake boot for E46 M3 has a perfectly smooth interior surface, engineered for the best flow and smoothest transision -- no sharp edges or angles to hang up or slow down the air. Made in the UK using a 4 layer silicone design. Unlike the stock E46 M3 rubber boot, which is prone to drying, cracking and leaking, the Samco boot is virtually indestructable and ready for the rigors of heat temperature and extreme conditions.

This Samco silicone intake boot fits the following BMWs:
2001-2006 E46 M3 coupe & convertible