My $.02: You might be able to progress faster than what Couch 2 5K lays out - but I would be very careful. C25K enables a number of our "systems" to get acclimated to running. If you do other cardio that will help in enabling you to possibly move faster than the program. However don't lose sight of the fact that a HUGE deal is you need to get your muscles, tendons and ligaments used to the pounding of running. Someone's cardio may enable them to progress erally quickly - but that strong cardio fitness won't stop an Achilles problem or some other problem. I've heard even bone densities change as we ask the body to do more. So going too fast could increase chances of stress fractures.
IMHO C25K is a guide. Some can do it faster. Some need more time. If you do it faster just be extra extra cautious.
"Kick off your high heel sneakers, it's party time."
-- From the song FM by Steely Dan
Yeah, what Haselsmasher said.
Disclaimer; I am a dirt trail bigot, and for pretty much any new runner I strongly recommend finding some good dirt to run on as this surface absorbs so much shock compared to pavement and allows you to strengthen your systems with a much lower liklihood of injury.
Fat old man PRs: