MACE PERFORMANCE 12MM UPPER MANIFOLD INSULATOR KIT FOR FORD LTD DC DF DL MPFI SOHC 12V 4.0L I6Exclusive to Mace Engineering, here we have our design registered upper manifold insulator to suit the Ford ED to BF series, fitted with I6 engines. 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 the intake cooler and increase low