Polishing the intake

I have an extra intake for my new engine and I was wondering if I was to polish it how much horsepower would I possibly gain? If its less than 2-3 I will probably just foget about it. Also where can I get an after market intake? I have only saw two and they were for use at 7000-10000 Rpm and theres no way in hell I turn that many on purpose.

Porting and polishing the intake manifold will gain some hp depending ont he other mods done to the head and valveltrain. I believe skunk2 is about to release an intake manifold for the d series.:)