no
for 2gb 1.6.8
550
   { "id" : 6, "intensity" : 27,  "worksize" : 12, "double_threads" : true},
 GPU6 :    504 H/s [T: 49c, RPM: 0, CC: 1050 MHz, MC: 1950 MHz][BUS:4]
560
   { "id" : 7, "intensity" : 27,  "worksize" : 12, "double_threads" : true},
GPU7 :    488 H/s [T: 53c, RPM: 2635, CC: 1050 MHz, MC: 1850 MHz][BUS:2]

for 550 4gb 1.6.7
   { "id" : 0, "intensity" : 54, "double_threads" : true, "worksize": 12},
 GPU0 :    416 H/s [T: 51c, RPM: 2833, CC: 1090 MHz, MC: 2050 MHz][BUS:1]
same 550\4 in 1.6.8 only 380-390 h\s