See the attached comparison image. The Transformers 2 Bumblebee "bumper" is the LT/LS fascia with the bottom lip painted black matching the lower grill. Also, the inside lip of the upper grill is painted black. The only thing different is the ground effects, which are similar to the GM ground effects but curve the the fascia a little better. The only things significantly different are the fog lights.
So if you want to have the TF2 bumblebee effect, either paint the two spots black that have green arrows on the attached image, or buy high quality black vinyl and have a shop put it on for you. I know
Ridergraphix sells the grill lip portion but I don't think he has the lower grill portion in vinyl.