2003 Mazda 6 S struts upgrade

2003 Mazda 6 S
My 2003 Mazda 6 S needs new front shocks. I was thinking of upgrading to some performance shocks. If i upgraded the front would I also have to upgrade the rear? or can I just upgrade the front? (on a very limited budget).
2005 Mazda 6S Hatch Lapis Blue MTX
Based on the age of the car, definitely replace them all. Unbalanced suspensions are dangerous.

Sent from the wrong side of the tracks.
Mazda 6s Wagon
The Pro Kit was designed for stock shocks. A KYB GR2 would be a sufficient replacement. If you wanted adjustability or longer life with added control the Koni sport or Bilstein B6 are frequently used.
I have Racing Beat springs and older KYB GR2's and they perform reasonably well. My next pair will be the Koni.