To make this a cluster program you simply up the weight to 90% but take a 10 second pause between reps. Make sure you rack the weight between reps. You do 5x5 in this fashion. 1 rep, rest 10s, 1 rep, rest 10s, 1 rep, rest 10s, 1 rep, rest 10s, 1 rep, rest 3 mins. Repeat.