These stainless allen-head bolts are a good addition to any set of headers, or ported exhaust manifolds, or if you just want to dress up your engine bay a little.  These bolts have a 6mm allen-head and retain the factory torque specs.  Kit comes with all 12 bolts for bolting the exhaust manifolds or headers to the cylinder heads for 3100, 3400, and 3500 LX9, 3500 LZ4, and 3900 engines