When porting the heads, porting intake boot to match was always necessary, but not the right thing to do Nearly 50% more volume and 1/4?" longer neck for more horsepower and torque Billet intake manifolds are a must have for those with big bore or boosted motors Includes two billet aluminum intake manifolds, manifold boots, and O-rings Stock boots are extremely small and do not flow well. MANIFOLDS HIGH FLOW XP900