Upgrade 29er Fantom DS Rear shock

I just got my Fantom DS 29er this last week and new I was going to upgrade the fork but did not realize the rear coil shock was so bad! I figured at least it would give decent rideability until i wanted to upgrade but after one ride on some really smooth single track I have decided to replace the rear now. It has a bad rebound thud that makes riding it not so fun. I would like to stick with a budget coil shock and found one on amazon from
DNM Damping 2 System Mountain Bike Rear...

Upgrade 29er Fantom DS Rear shock