MACE 6.35MM PERF. MANIFOLD INSULATOR TO SUIT HOLDEN COMMODORE VT VX VY L67 SUPERCHARGED 3.8L V6Exclusive to Mace Engineering, here we have our design registered lower manifold insulatorto suit the Holden series from VS to VY fitted with L67 Supercharged 3. 8L 6 cylinder engine. What are manifold insulators and what do they do? Manifold insulators are a thermal insulating spacer that mount between your engine block and intake manifold. Made from a heat blocking composite, our manifold insulators will increase power from your engine by keeping