Planes mod: I think it's a pretty awesome mod, good for exploring and finding enemy bases. Also it gives another oppertunity of air fights and taking out enemys in the air. The best part of it is (my opinion) that you have a reason to make another base or an underground special thingy whit an plane road (I ain't english sorry ^^). It's for MP.
Line Runners: People like to run behind the pvp line. Fixing that will improve PvP.
Leaving ender pearls enabled: Good for raiding and pvping.
Fireballs: Finding a certain mod which makes fireballs enabled to be gathered somehow in Smp.
Difficulty: Set it on Hard Please because this is a pvp hardcore server right? Mobs would be harder to kill zombies kill your doors etc.
Creepers: Enable their explosion for raiding or just because I always glitch in the blocks when they explode. (very annoying have to relog then)
Any good idea's? :S
*Edit: inform me what ya think about it pls