Complex sentence: In Spring 2011, Optimum Online Boost was replaced by Optimum Online Boost Plus for their consumer tier; for the same price, it increases bandwidth to 50 Mbit/s downstream and 8 Mbit/s upstream.
Split into simpler sentences: In Spring 2011, Optimum Online Boost was replaced by Optimum Online Boost Plus for their consumer tier. For the same price, it now offers 50 Mbit/s downstream and 8 Mbit/s upstream.