aldo: the engine-killing missile you speak of already exists: FS1's disruptor missile. I loved that thing...

Are you now talking about modding FS to support some kind of tournament racing game, then? It'd be pretty cool and different, yet not require too many ship mods. Plus, it would be like wacky races.

In addition to kinetic weapons, disrupting and energy draining weapons would be a good thing to have. However, if you're talking about indirectly killing people by smashing them into things, why not just give them the opportunity to buy guns - only make them so horribly expensive they sacrifice other stuff in return.
And if energy-draining or damaging weapons are to be used, shields should also be available to purchase.
Hell, I'm talking about a 'purchase' and balance system of play that I'm not even sure the FS engine would take. However, I'm sure the source-coders could manage, though it's need a new front-end (or a heavily modified one).