c0bra_99

I want to say thanks for this awesome forum! Its great to be around so many mustang owners and enthusiasts.

My 99 cobra has this intense vibration at high speeds, mostly during deceleration. Kinda reminds me of those cuts in the fog line that shake the life back into you.

The problem began after I had a ford dealer in Oregon put in 3.55 gears in it.
They installed a new ring and pinion, new clutch pack and all the bearing. set the backlash to .009 The pinion depth .028 and 25 inch lbs preload. Filled with 75w140 and friction modifier. They also replaced both u joints.
There is a slight cupping on one of the inside front tires and i plan on replacing them after i modify the profile of the car.
The vibration is so bad everything in the car rattles and it seems to be worse when its first driven. I know the first thing going to be said is "its under warranty take it back" and I will, but first I want to try and get some ideas why its happening in the first place and also get my feet wet in these forums. I dont trust many people with my car and usually do the work myself but really know nothing when it comes to back lash and pinion depth. Thanks