Just checked on a Roush site (Fnsweet.com) and a lot of mixed comments on the upgrade. Seems like most would just go with a tune and parts from VMP, JDM or Brenspeed. Some worried about loosing the warrenty. The Phase ! is rated at 575HP and 515 rwhp. The 625 kit shows to be getting 547 rwhp. Ray Skillmans on You Tube has dynos of both.
2015 Stage 3 Roush
'66' Ranchero w/almost done 302 T-5 swap
2000 4x4 Ranger
2003 4x2 Ranger
'69' Fairlane Cobra, 428 4-speed waiting for work