Fuck IRS, I'd rather not jar my spine loose from wheel hop. With the power it's putting down, it would snap the IRS bad. The competition wasn't horribly fair, but I'd personally rather have the GT500. Just looks like a hoot to side step the clutch and roast the tires.
At the same token 4,000lbs vs 3,000lbs. Don't take a rocket scientist to figure power to weight ratio.