[lutusp]

Cosmic inflation changed the expansion rate of the "explosion", but this doesn't mean there wasn't an explosion.

Cosmic inflation changed the density ratio between spacetime and mass/energy, but the entirety of the universe's mass/energy came into existence at the moment of the Big Bang. So yes, some explosion that.

Remember about this particular explosion that it wasn't an explosion of mass/energy into the empty space of a pre-existing universe, but an explosion of mass/energy and spacetime into nothing -- the Big Bang was space, time and mass/energy.

In other words, there was no "before" before the Big Bang, and there was no "outside" outside the Big Bang. The Big Bang was everything.

More detail here: http://arachnoid.com/gravity