if you have a Spec R, I'm not entirely sure there are any for your car, your engine possibly uses a BB turbo which shouldn't be an issue but the 440cc injectors will be, the standard injectors for an S14/a are 370cc (which the maps are built around) i don't recall any maps that use the increased capacity squirters.
if you are looking for a marginal increase on your current set up, i would probably go down the SAFC2 and map route...i did this on my 14a years ago (after installing S15 440cc's) and got around 300bhp an SAFC can be picked up for maybe £100 and i think the mapping cost a further £150 through APT
if you are looking any further than 300ish bhp i would look at throwing in some 740's and then getting a proper map done but it won't be cheap (ECU..say PFC & Map could run into £800 at the least) then you'll almost definitely want to change the turbo...welcome to the slippery slope lol