the question which one is better for the b18b1, better yet what benefit is there for a nonstepped and stepped exhaust manifold? i love toda and spoon parts but too bad i can't fit them on my b18b1. toda has stepped headers...why?...while spoon doesn't...why not? i've heard that stepped exhaust manifolds is designed so there isn't any reversion of the exhaust gases back into the cylinders...but is there a performance advantage....i'm looking at comptech and greddy headers....comptech is stepped and greddy is not....which one?