where does one start....
have a look at this part of the forum, this will answer all your questions or worries...
http://www.skylinesaustralia.com/forums/RB...sions-f184.html
also look at this thread about rb30 hybrid motors and results...
http://www.skylinesaustralia.com/forums/Rb...yn-t104332.html
it may also be worth just building up your rb25, as you dont have to go to a hybrid motor to make good power just ask fineline...
I personally took this option also due to wanting to make it out of an rb25, not to mention insurance and the rev'ing qualities of the rb25 vs the 30...
It a depend on your purpose of use, and what your future plans are... But have a read too...
http://www.skylinesaustralia.com/forums/Rb...yno-t55845.html