Hey mate im running 18 x 9.5 offset +25 on my 33 gtr.
You havint really told us your offset you have only told us the width?
I have also put 19 x 9.5 with +20 offset. and they fit without scrubbing.
http://www.skylinesaustralia.com/forums/Wh...-Sk-t84208.html
Mate that is over-fueling. I would be getting an ecu and a tune in there asap, before you are hitting the limiter. As for the boost. Do you not have a boost gauge?