If you are going for a remap you would have to go to Jeff, he was one of the first in Australia to do remaps and he is definitely one of the best, and as for cost he'll be around the $500 mark but every tune is slightly different, and touch up tunes are a fifth of that
If you want proof of his work he was the one that kept this standard RB20 together when it was making 370rwkw.
http://www.skylinesaustralia.com/forums/Tu...p;hl=Turbo+Tune
EDIT!!
His number is; 0434637357