They exist. I've tried to test them but if I recall correctly they didnt fit in the housing.
The only way you can get a truly bright reverse light in this car is to modify the housing and you will likely need to code the car as well.
The stock housing has a flaw in its design form the start, combined with minimal room the housing and reflectors point upwards.
This leaves any upgrade with the tendency to point into the sky, which is the last place we need light.
http://www.highperformancebulbs.com/hpx921hidrel.html
If you search for hid reverse lights you can get one for nearly every type of bulb. However, they are not guaranteed to fit in every car as housings differ.