14PSI will not last very long on a stock turbo either. Do a search "r33 turbo max boost".
Stock Inj + bump the fuel pressure will get you a tad more power (whatever the number on the dyno reads)
After that you can throw what ever turbo you like at is, no more power. Your tuner is telling you turbo and rightly so. The stock turbo will not
last long at 14PSI. Do you want to be cleaning comp housing shards (yes yes the rear blows out, but it unbalances the shaft and the comp wheels generally grinds a nice path up against the comp housing) out of your intercooler?!?!
So basically you need to do all four, turbo, inj, pump and afm.
Also whats up the with e-manage? Just asking seeing 90% of the population use PFC, the other haltech, link, vipec etc.