u dont get the 3 litre donk there in teh us of a do u?
bummer u
well
i would go with rb25de - not that much heavier than rb20, plus more power and torque (a bigger torque increase as bore size is the same - its only the stroke that adds more displacement)
indiividual throttle bodies would require custom fabrication i assume as i dont think anybody manufactures them for the rb25 (i think they r around for the rb26 tho)
exhaust side go some decent extractors and around a 2.5 inch exhaust
get some cams put in if u want - there are nismo manufactured cams for the rb25
management - use the standard ecu for 'run in' if u do any internal work (this includes head work) then u cant go past Apex'i SAFCII (cant think of any others of teh top of my head - somebody help)
just my info