Review on Dorman 03413B Exhaust Manifold Hardware Kit: Fit Select Models with Precision by Ikki Martini

Haven't fitted them yet as the engine is still disassembled so felt I couldn't give them the full 5 star rating. But these screws appear to be a quality product. I don't see any sloppiness in the workmanship and in the test they screw themselves perfectly into the head. They are stamped 10.9, like the factory. I will install them according to the order and torque value listed at the GM plant. Time and heat cycles will reveal their true history, although the original bolts have been known to break. Maybe after a few years of use I'll have a reason to up my rating to 5 stars.