Chi-Town SRT/6,

That excellent 'hook-up' you speak of is probably the ESP kicking in. I presume you are launching without the traction control on. If so, then the ESP is only about 80% reduced in it's intrusion of your launch. It will eventually kick in and keep you from frying the rear tires completely by slightly retarding your timing.

This forces the engine power down, just a bit for a split second or two and let's the rear end 'hook-up'.

Hope that helps.