I was looking at parts to change a G35 to a skyline and it said it had a VQ30DD. I looked more into it and it's a direct injection fuel system. It's called Neo-Di It's for a FR format but wonder if that engine would fit in are car. engines HP produced 227-240HP while are DE produces 217-222HP.
Link to NEO-Di Info http://www.nissan.com.my/cor/why/environment/neo.htm
Also for you 2k2-2k3's and possibly 2k4 I found a VQ35DE high power control ECU made by IMPUL it's for the G35 and Fairlady Z but wonder if works with your cars. The price I found on it was $1,513.06.

 

$1500 on an ECU

 

well, if its a Nissan "friendly" standalone ECU its worth every penny...from the looks of that pic thats exactly what it appears to be being that it has all those ports on it...

 

great signature

 

The D stands for DIRECT INJECTION I believe and you'll be wasting your money as that won't work with our cars...