I have a Roush Sport which I have added Roush Part # 401296 which is the Stage 2 full
suspension kit.
The kit you are refering to is the new trak Pak kit. It kicks up the basic roush
suspension (like I have) to the trak pak specs which is for guys who run their Roush on the track but also drive on the street. (Don't forget the forged wheels !!$$$)
For me, I don't drive mine on the track and I am very pleased with the gains seen going from a stock mustang GT
suspension to the
basic roush
suspension.
You may want to visit fnsweet.com, some of the members there have gone with the
suspension kit you mention and some outright own the factory trak pak cars. From what I have heard the trak pak is awesome.
For my feeble opinion, the basic Roush
suspension ($1200) is awesome too. I can tell a whale of a difference over stock. Given the Ford Racing and Roush kits are about the same $ I'd go for the Roush, although I have never driven a Ford Racing suspensioned car so I suppose my opinion is one sided. I can tell you for the $1200 the car is worth every penny of it just being safer, more stable..............not to mention the performance gains. The car is solid.
Jack