SE Manifold #29636-99 vs. stock H-D #27019-89

[JamesButler]

For an Evo w/ ported heads, bumped c.r., a mild bot-in cam and CV-40 carb, is there any power gained by swapping in a Screamin' Eagle manifold (#29636-99) over the stock manifold (#27019-89)? 

Any downsides, such as reduced fuel economy or re-jetting required?