depends on what you are chasing...
ive had both now & this is my opinion:
- if u want effortless/lazy power, ball tearing mid range & an engine which is not as free revving, build an rb30.
- if you want more of a drivers engine where u need to be in the right gear & its sounds like a gtr should do, build an rb26.
- option 3, buy an r35 with 3.8ltr if u want REAL torque (just apply for a mini house loan)