I've used the Savox 1257TG's for the last 4 years and have had great success with them. I've only burned out 1 1258TG but she was hammered on in a 4wd sc. I'm going to be switching over to Xpert though, Im going to try the SI-4431. The specs look really good:
Dimensions: 40x37.80x20 mm
•Weight: 62.50 g
•Speed: @4.8V: .100 sec/60
@6.0V: .080 sec/60
@6.6V: .070 sec/60
•Torque:
@4.8V: 14.00 kg-cm (194.93 oz-in)
@6.0V: 17.50 kg-cm (242.90 oz-in)
@6.6V: 19.25 kg-cm (267.19 oz-in)