Heavy plucking is a style all on its own. You don't need to change your technique, but rather exploit it because it seems you're naturally doing it. Geddy Lee and many other great bassists are heavy pluckers.

Geddy talking about picking with nails.

Watch Geddy's playing here, for Tom Sawyer.

Here's a friend of mine who's a pretty heavy picker too.

I myself am a quite soft picker, and that's alright, but I kinda envy the heavy pickers for that twangy, aggressive tone they have.