malibu trans

[bulldog389]

I have a 2000 malibu with the 3100 and my trans feels a little weak. It shifts at about 5500 around 45 mph when I floor it, but it over revs before it shifts. I've learned to let up at about 5000 and it will shift smoother. Any ideas?

Is there a stronger trans that I can swap in or maybe could I rebuild this one with stronger parts?