Originally posted by WC
414 should be pretty neutral handler.
If your rear end is THAT loose... 
1) make sure your Drag Brake is turned Off
2) run your rear diff loose (as loose as possible without slipping) or swap it for a gear diff from a TA04
3) how's your rear tyres wearing? Check your camber.
4) remove rear sway bar
In addition, it can be very useful to alter the rear roll center to add more rear roll.
Or using different tires front/rear.
I find it's nessecary with at least one degree of toe-in in the front. Less will make the car very twitchy.