B58 engine sodium-filled exhaust valve TEVI-1058-HS for M340i, 540i, Z4 M40i, GR Supra A90

Supertech TEVI-1058-HS is a genuine sodium-filled exhaust valve built for B58 engines in the M340i, 540i, Z4 M40i and GR Supra A90. Designed for fast-road or track-day use where stock valves struggle with heat.

Features an Inconel/Nimonic head and hollow sodium-filled stem for superior thermal management. Not a generic 'OEM replacement' - it’s a functional upgrade for stage 2 and beyond.

• Stem diameter: 0.234 in | Overall length: 3.940 in | Head diameter: 1.122 in
• Single valve - requires Supertech 6 mm single valve lock conversion and intake integral stem seal for full fitment