Stack both. I’ve never used SR9009 but I’ve heard good things, and I LOVE cardarine, it is my favorite non steroidal compound out there. 20mg of cardarine preworkout, or in the morning is solid.
Only used GW before but that shit is freaking awesome. The 3 months I used it, honestly I would have days where I nearly started digging a hole in my backyard, just because I had so much energy/work capacity. You’ll love it and the SR9009 should work synergistically.
GW you only need to dose once a day but the 9009 will have to be done through out the day.
That being said together used is one hell of an endurance stack. Of course GW alone will give you a great edge on recovery and optimal cardio output. Combine both of these together and you should be very well suited for any cardio exercise. I love using these when my diet and regiment are really dialed in cause then it shows me how I can elevate my performance I another level.