dude, i dont think you can do much better than that
i have exactly the same specs, and i get about 350k/s a tank around town
and about 550 on the highway
doesnt matter whether i baby it off boost the whole tank or not
any money says when you reverse, you can smell fuel also
ive replaced my o2 sensor, had the car retuned by matty spry (he said the original tune wasnt that bad anyway)
made a tiny difference (went from 300ks a tank to 350)
i think r33s are just thirsty cars
oh i have a 80ml throttle body as well on a forward facing plenum