I think IRS is overrated. If the new Boss was fitted with an IRS it would be 200lbs heavier and slower and cost 2000 dollars more. As it is now the solid axle pulls over a 1G cornering and can beat an IRS equipped M3 BMW. Im hoping in the future Ford offers IRS as an option not as standard equipment. That way the drag guys would be happy and the IRS people would be happy.