The reason the new cars dont have IRS is due to the fact that it costs more money so to keep the cost down and the price more affordable they use a solid rear axle.
The car handles just fine, its people not knowing the cars limitations or their own that really causes problems. For example in the past I had an 82 Trans
-Am, no ABS, no 4 wheel disk brakes and certainly none of the handling of todays cars, muscle or otherwise.
On occasion I drove that car in the snow, ice, in extremely wet weather etc without ever losing control of the car. Did it suck? You bet it did, but with patience, vigilance and knowing the car's limits and my own I still managed to get around in bad conditions when it was necessary.
All I'm saying is, know your car and what it can and cant do as well as yourself.
It goes a really long way to help keep you and others safe.
1995 Mustang GT 5.0
BBK CAI, Pro-M 75mm MAF, Pro-M Optimizer, BBK 70mm TB, GT-40 Intake, 24# Injectors, AFR 165's, 1.7 Roller rockers, Crane 2040 cam (E-303) BBK Equal Length headers, BBK O/R X-pipe, Flowmaster American Thunder 2 Chambers. FMS 3.73 Gears, Lentech AODE 2800 stall, BBK 255lph Fuel Pump, BBK Fuel Pressure Regulator. MSD 6AL, Steeda UDP's, FMS Aluminum drive shaft, Autologic chip Larocca tune.