Mmh, I haven't done any fasion-mods -yet- (waiting for a liq. cooling system to add a touch of fluorescance and a blacklight... then I'll add a window). But both my main cases have an extra hole in the side of the case. Extra cooling...

I did mod an UPS a while ago 'tough. Tore out the old batteries, which were dead and too small imho, and replaced em with 2 car batteries. It boosted the capacity of the damn thing by 250%...