Recommended for maximum competition LS engines with 4.155 inch bore or larger. Drag race, maximum competition, naturally aspirated, heavy nitrous or forced induction applications. Dart's New Race Series 10 Deg LS cylinder head is the ultimate choice for maximum competition. Designed with raised Pro Stock oval ports, canted valves and highly efficient wedge style combustion chambers, the Race Series 10 Deg LS is a radical departure from traditional LS heads in one other area. The intake and exhaust valve locations for each cylinder have been reversed. This feature has been the standard for maximum power wedge engines for decades. It is recommended that you contact a Dart technical representative before placing an order for this item. Detailed information about your planned engine build will help to ensure that you choose the right configuration for your motor and that any special parts are taken into consideration.