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I'm not sure if the sling shot effect is due to a distinct lack of traction with RWD, or horrible turbo lag :?:. However, check out the sound of the GT2 on the second pass :-P:

I'm going to guess that GT2 has really tall gearing, bad lag, and unwilling to snap it's half-shafts on a hard launch. The 911 has far less drag, even if the Cd. is higher (Remember, it's total frontal area that matters most), and that coupled with insane power levels... :)

That GTR is fast, that is for sure.