There are a number of mods which add much finer control over fuel management and better aerodynamics to KSP.

Ferram Aerospace[1] adds much more realistic aerodynamics and TAC fuel balancer[2] adds a fuel balancer.

[1] http://forum.kerbalspaceprogram.com/threads/20451-0-22-Ferra...

[2] http://forum.kerbalspaceprogram.com/threads/25823-0-23-TAC-F...