Check out the new Comp Thumpr cams. Not a lot of reviews so far, but apparently, they manage to get some power AND that choppy idle you're looking for. But...
You can get decent idle quality and nasty sound with better than 'off-the-shelf' cams. Any good shop, like SD for example, should be able to custom spec a cam for you.
http://www.thumprcams.com/