base your decision on what your planning to do for upgrades and power output. If your planning on keeping stock internals then 740's are simply a waste, you wont ever use anywhere near their capacity, will get worse fuel mileage and idle will be tricky to tune for smoothness. 555cc injectors are good for well over 600bhp (525-550rwhp ).
If you see yourself doing full internal mods and big turbos for a 650bhp + engine then sure go for the 720's so you wont have to upgrade again.
1990 Twin Turbo 5spd Stillen Stage XI+ "No Show,All GO" 1999 Maxima SE 5spd
ECZA member #0314
..."If it doesnt make it faster, I dont care"...yellowZXTT