i was wondering if it is hard and how much it would cost to put a twin turbo kit on the RB26DE engine. like how much do you guys think it would cost to put like the exact twin turbo kit that the RB26DETT has? and do you think it owuld be worth it or would it just be better to buy the gtr model  

the RB26DETT is a whole different motor.  Dont think that the DE is the same motor just without the turbos, there is much more to it.  you would have to completely build the motor itself to be able to boost it.  the RB26DETT is already made for boost.

Definitely go with the GT-R (if its even an option).  good luck.