Minimum velocity for particles

I've been messing around with the particle system Unity ships with, and I gotta say it's definitely nice, but I think it might be missing a fairly fundamental function, unless I just couldn't find it.

Is it possible to have all particles escape from the center at a certain minimal velocity?

What I'm going for is a 2D version of a fireworks explosion where I can't have some particles just kind of wriggle in the center. Everything needs to get repulsed outwards. I just can't seem to find anything that will make that happen.

Is there a way of doing this or do I need to look for alternative solutions?

Set the Z tangent velocity. Fireworks would also generally use one-shot.

Does Unity 4 have tangent velocity for particles? Just downloaded it and am going through a tutorial that was done with 3.0.