IRS is independent rear suspension, 99-04 cobras have it.
The springs will work fine, they offer the same drop. Only thing different is that sport springs for 94-95s in the rear are 250-285lb/in while 96+ rear sport springs have a spring rate of 205-250lb/in
im having second thoughts about lowering it, i got up under it today, its got longtube headers, that i didnt know it had on it, and an x-pipe that hangs sort of low
They will work, and I would still lower it and get rid of the 4x4 look. Edit: I got the Maxspeed Lowering Springs and I love them, they are cheap and I was kinda scared but come out really good!