My VE was slow too (for the price!), thus I'm upgrading it with a Loller Rocker
N1 cams don't usually like to be activated 4500 or any lower. What I usually do is do a dyno run on low cams only and then do a another run with high cams only. Overlay the two graphs and bam where they cross is where you should activate.
If you get a NismoTronic ecu, you can activate cams with any of the 4 outputs, AC, EGR, AIV, O2 Heater. This lets you do individual cam activation too.
N1 cams have very smooth ramps, on a 20VE, you can rev it to 9k rpm and you shouldn't get valve float. Granted it's not a bad idea to have stiffer springs in-case you miss shift, but how often do you miss shift and go above 9k rpm?