My hope/guess it that the self-destruct module won't deal damage by itself but instead add a modifier to your standard on-death explosion that'll be coming.
That explosion was ( I think ) already confirmed to be based on bot-size. So I'm thinking that if you blow yourself up with the kamikaze module then it'll add like a 250% modifier to that.
Meaning that a heavy mech blowing up won't just take out nearby damaged light bots but also fully repped light bots without shields and damaged assault bots. But an intakt blowing up will stull cause only minor scratches on a mech without the module and a dent at most with the module.
*Insert really awesome sig here*