I'm enjoying my Arrma Senton but I found that the bumpers are far too rigid and break easily. I ordered the T-Bone Racing bumpers after breaking my fourth set of stock bumpers.
So far they are holding up much better than the stock ones. I've run into several solid objects at considerable speed and they absorbed the punishment with no issues. They seem to be much more substantial than the stock ones, but also allow for some flex which I think is the key. Note that they stick out a bit further than stock but I don't find this to be an issue and they do look nice.
My only suggestion would be to include some instalation instructions. I found the videos online but a diagram of which screws to use where might be nice.