Not a real lot of difference in the s/s m/s, i've always gone with m/s because it's cheaper haha. Some people have preferences, some say m/s soaks heat more than s/s etc, some say m/s is stronger... Ramhorn are good set ups, but i'd always recommend ext gated set up over internal set up, whatever style manifold you get. I've had Evo style, top mount, power up style and ram horn, they have all been spot on tbh... do love the top mount though!