Congrats on your Matrix and good radio by the way.
Assuming your buggy has the cross-pin upgrade in the diffs, the first thing I would upgrade is this
http://www.amainhobbies.com/product_...ducts_id/12819
Then I would maybe get a set of CNC Aluminuim Steering knuckles
http://www.amainhobbies.com/product_...ducts_id/12791
If you have anymore questions regarding your Matrix, feel free to pm me. Good luck