Im not sure what you mean by "enhance its performance". I would not even try to change its performance. I would have the tranny rebuilt to factory specs. Replace whatever parts are necessary. The vibration generated by your tranny is an indication that there are hard parts making contact with each other internally. This is very bad and gets expensive. Only the soft or friction parts are designed to make contact with each other. So there are some serious problems that will only get worse. The firction parts are relatively inexpensive but hard parts get costly fast.
If I were you I would have it looked at ASAP. I would plan for 2-3k dollars to have it fixed. It could be less if you are blessed. Either have it rebuilt by a competent rebuilder or exhcange it for a factory MB rebuilt unit.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k