There was a quick discussion on manifolds on one of these threads the last couple days.
OE Mani - worst.
Franken Mani - Better then stock
JBS Mani - Best
My consensus on the whole thing... Anything with more flow then stock will result in net gain.
I myself am most likely getting the frankenturbo mani as Im also doing a mild build with the F23. Id love to get a hold of that JBS mani, but for ~$700, Id rather spend my money elsewhere. Not to say its not worth it (as Im sure it is) just due to possible future plans, its not worth it for me personally to dish out for the best of the best.