I really didn't like how long Bumblebee's legs were and that he was as tall as Prime, so I did a little mod to fix that.

1-Take the lower leg off. It’s a pressure joint so quite easy.
2-Remove the two screws that hold the leg together.
3-Take the slider piece out. This is what you will cut.
4-Here's a shot of both sides of the slider. The dotted line is right where you want to cut.



5-Cut the "B"!
6-The lower piece is no longer needed and even though it looks like you just cut off some crucial stuff, it still hold together just fine in vehicle mode.
7-Place the slider back in and screw the leg back together. I left the cut alone but if you want you could glue on a piece to the bottom to close off the loop. It really isn't necessary as the leg holds together very well and I haven't pulled it apart yet while transforming it.
8-Repeat steps 1-7 on the other leg. Snap the legs back on!




A happy Prime with a shorter Bumblebee.




And transformation is unharmed. The only drawback is that the back wheels can flex in and out more.

Funny you ask, here's a "before" shot from a couple weeks ago!