The more important part is the drill. Drilling a 3" diameter hole in steel is fairly demanding so having a hand drill with good torque that can keep cool at low RPM's is most important. I burned up my dewalt drill that had a max speed of 2700RPM doing my first hole. It didn't have enough cooling at 2-300RPM, nor the torque. Bought a milwaukee with a max speed of 850RPM and that ate right through without issue.
Their strut opening tools are great! I purchased one for the S550, and the shop that installed the new springs, and camber plates liked it so much they purchased it from me for what I paid Vorshlag originally!