The Extreme Pack Add-on for Steep has 6 achievements worth 100 gamerscore.
Obtain the Gold medal in 10 Challenges of Extreme Pack
Obtain the Gold medal in 5 Challenges of Extreme Pack
Finish the Trial ROGUE 4 of Extreme Pack
Take off and land 5 times in the same Speed Riding run (Extreme Pack DLC required)
Fly for 5 minutes with the Rocket Wingsuit (Extreme Pack DLC required)
Safely land after jumping from all the 7 Base Jump Spots in Alaska (Extreme Pack DLC required)