Shrinkage is the big issue. It'll be hard to stretch that back in place.

Generally, this is the kind of thing that you're better off picking up a replacement panel for since they are still cheap.

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2011 M3
2006 Sierra 2500HD 4WD LBZ/Allison
2004 X5 3.0i 6MT
1995 M3 S50B32
1990 325is
1989 M3 S54B32

Hers:
1989 325iX
1996 911 Turbo