Im not running anything right now cuz shes apart for the winter lol. I plan on doing EVERY mod other than bigger mani's. Only gonna do the tweaked mani's. Including stacked pulleys. Just got my ypipe and SC inlet ported and coated and i polished my intake runners. I would assume 550's are needed after the extent of those mods. If not, why was it ever a topic of discussion or available for us at NW's? No mod is every really needed (aside from supporting mods obv). They may not be needed but that doesnt mean there are no benefits from them either.