You might be able to help it spool up to full boost a bit faster by keeping it fully shut longer... or progressively opening it up a bit early to avoid a boost spike past the set value... Depends what alterable settings your EBC actually provides. Either way, you're not going to be able to:
1. Take advantage of the altered boost curve without a touchup tune to take the different airflow into account. 2. Visibly see what differences its making to the boost curve without graphing PSI to RPM, once again, on the dyno. You COULD see how different it feels by changing it and then taking it for a drive, but you're risking bad air/fuel mixtures (and it'll feel slow, even if you've nailed the best possible boost curve for your engine, because its not tuned for it)