You could look for a 19 Turn motor. That will provide you with the best combination of low end torque and top speed. You can look for the Trinity Komodo Dragon :
http://www3.towerhobbies.com/cgi-bin...?&I=LXMDY7&P=7
Or you could go for the Orion Element:
http://www3.towerhobbies.com/cgi-bin...?&I=LXRTY2&P=7
Both of these are great motors and provide tons of power. Which ever one you choose will not disappoint.