We do not recommend any of the aftermarket heads for daily driven street cars due to the extreme overheating problems (over 30% less cooling surface) and/or lack of proper flow/air speed as compared to a properly modified VW factory head. In most cases our GB 856 heads out perform overall any aftermarket street head, even with 42mm by 37.5mm valves and our VW ported heads normally provide 10 times the life. We continually see the aftermarket heads broken in half or are so soft that the seats sink into them. This is because the material's (being used) heat treatment is being radically affected in the head temperature range that a VW runs in. If heated and then cooled with the fan, they get brittle. If cooled without a fan they get soft.