Can you Curse away spell resistance?

I'm finding spell resistance to be a major pain for my spellcasting characters, and I'm looking for clever ways to minimize its' impact. I've already got Spell Penetration, focusing on spells that don't allow SR where possible...the ususal stuff. But I'm looking for a spell/item/effect that either lowers a target's SR, or boosts my ability to overcome SR, and I'm drawing a blank.

The Bestow Curse spell says you can invent your own curse effects, as long as they're equivalent to the existing effects in power level. Would it be fair to allow Bestow Curse to lower a target's SR by, say 5 points? 10? You would have had to beat the target's SR for the spell to take effect in the first place, so it's almost not worth it... is there a more clear-cut way to do this that I'm missing?

Thanks.