TRACTUFF K24/RBC COOLANT BYPASS UNITThe water bypass allows RAA, RBB, RBC, and RSP cylinder head (K24A and K20Z) owners to run the more popular aftermarket intake manifold options that were designed for the earlier PRB PRC cylinder head flange. The PRB PRC style manifolds do not have an integrated coolant passage so the coolant bypass hole is left open when used on RAA, RBB, RBC, and RSP cylinder heads. Even if you don't plan on running a PRB PRC style manifold there are plenty of