I have yet to actually drive a Cobra or any mustang with a IRS. Mine is a DD that I want to make a little more nimble in general. I have no "goal" for the car ie. drag car or track car. I'm doing mods that actually work. I put on rear LCA's with a spherical end, I have 4.10's awaiting install. Aluminum DS will be next followed by FLSFC's then prob stop. I'm glad I didn't go IRS with all the money it would take to beef it up. I'm stock power wise too. I have asked people from amature auto-x guys all the way to championship holding roadracers...and they all say to stick with SRA. "All the fastest cars in the American Iron are a SRA car."-Paul from Paul's Automotive here in Cincinnati. From what I have read/heard, that by the time you mod the hell out of the IRS to be a GOOD rear, you have taken the IRS out of the IRS...stiffer springs etc. I've been wanting to drive a car with PHB/TA and see how comfort is. No I don't want a Lexus but I do want a agile "muscle car". If I can do all those mods and it rides relatively like stock...I'm happy. I also realize that you have to give a little to get a little. Give up some quietness and gain some NVH.