I installed both bumperettes and the diffuser today.
Bumperettes from Bumperplugs.com: A+
Perfect color match and they look great.
Diffusers from ebay: D-
After going through the whole process of removing my bumper and installing the diffusers, I ran into a couple of issues.
1. the provided hardware was too short.
2. once I got everything tightened up, the inserts in the fiberglass pulled out.
3. I'm not too happy with the overall look of them as they look like they are added onto the car.
Needless to say, I'm not too thrilled with them and I removed them.
Stock
With Bumperettes and Diffusers (before I noticed that the diffuser inserts were pulling)
Without the diffusers