From my limited understanding of LimeWire this is an automatic feature. In the basic version you connect to 3 UltraPeers(Excellent), in the Pro version you connect to 5 UltraPeers (TurboCharged).

Now if your connection is good enoungh LimeWire may make you an UltraPeer with Peers and leafs connected, when it is needed by the network. Hence the turbocharged in the basic version.

Normally for this to happen your ISP must not block/filter p2p applications, and LimeWire should be configured for optimal performance.

You can also disable or enable this feature in LW tools>options>speed