zex camshaft question

Im pretty sure im going to get the ZEX stage2 camshaft for my d16z6. But on ZEX's site they say you dont need to upgrade springs and retainers, but on Nippon's website they say you need springs and retainers. Wich one?! is right?! Im probably going to get the springs but i didnt want to have to buy titanium retainers also. Do i need to? And also would i need to upgrade my ecu? my brother said i should to get my higher redline, but would i be ok for a while cause i dont think i have enough money for that yet, will i still get 10-14 hp without the ecu upgrade?

Whenever you change camshafts you should work in the whole valve train. As far as upgarding you ecu. Not true. Your rods and rings will still not be able to handle higher rpms. Factory redlines are set because that's what the stock internals are rated to handle.