I reccommend a FPR for any boosted car that didn't come with it a turbo. The stock Honda regulator is okay, but won't hold up to the boost necessary for 200+ hp accurately. It needs to produce [your intake pressure at any given rpm] + 1 PSI of fuel at all times in order for your fuel maps to be manageable. I hate the B&M unit because you can't turn the pressure DOWN which is necessary with any pump bigger than the 190lph.

Aside from that, the stock filter's banjo fitting is a restrictive cross-drilled dickhole piece of crap. Don't worry about the rail being a restriction. When you get to ~220hp, that's more likely to cause problems than the rail.

The reason most people replace the rail is that they get to use -AN fittings to make plumbing an upgraded fuel system easier and more serviceable. The AEM rail can easily be fitted with -6AN fittings. It's pointless to upgrade the rail without upgrading the lines and filter, and using a quality regulator like an Aeromotive. If you do all that to a D-series, it had better be a show car. It doesn't cost much (~$350 to do it right), but you'll never use its potential without at least another 2.0L of displacement.