I've been told that the stock intake doesn't become a flow restriction (with an upgraded filter) until about 460RWHP.
I've got a similar setup to yours, and have been told that any gains I see would be minimal at best.
Most people suggested cooling mods, or a diff brace at my (our) power level.
What size filter are you running now? Are you running just a big filter on the stock tube with no air box around it? If so you probably wouldn't gain much by just swapping the tubes, I swapped them just for looks.