MINI Cooper strut tower mushrooming
Nearly every 2002 to 2006 Mini has this problem. Unless your MINI is very unusual, or rarely driven and then only on great roads, your front strut towers are probably already "mushroomed". The constant pounding of the strut into the tower causes the top of the strut tower sheet-metal to deform or "mushroom". This occurs because the sheet-metal used to construct the towers is too light of gauge.
Take a look at yours. The towers should be flat across the top. You can probably see the deformation with the naked eye, but to be sure, place a straight-edge across the top of the tower. A gap of 4-6mm is not unusual. As you might expect, this does have a negitive affect your front-end alignment and your car's handling.
In severe cases, the tower sheet metal will fatigue and tear. Avoid repairs costing hundreds by installing strut tower reinforcment plates. Some reinforcements mount on top of the tower and will not fix the "mushroomed" condition because the top plate of the strut can be warpped also. You can see this in the studs that are not parallel to each other. Plates that mount between the top plate of the stut and the sheet-metal on the other hand, will help to pull the deformed tower back into place and keep it there while reinforcing the area.