A packet co-processing system for improving the performance of an Application Specific Integrated Circuit (ASIC), including: a set of N search engines, logically disposed so as to form a chain of search engines, including: (a) a first search engine for connecting to the ASIC; (b) a terminal search engine, and (c) a set of N-2 intermediate search engines, logically disposed between the first search engine and the terminal search engine (N=2), and wherein each particular search engine includes: (i) an input selector including a parsing unit configured to: (A) select a particular set of fields containing at least a portion of at least one field from a larger, first set of fields submitted to the particular search engine, and (B) produce a Synthesized Key using data from the particular set of fields; (ii) search logic configured to: (A) search a memory, in response to the Synthesized Key, for a key entry matching the Synthesized Key, and (B) retrieve associated data corresponding to the Synthesized Key, and (iii) an output unit for outputting the associated data from the particular search engine, and wherein each output unit of each intermediate search engine, and at least one output unit of the first search engine and the terminal search engine, output the associated data to an adjacent search engine, and wherein the input selector of each intermediate search engine, and at least one input selector of the first search engine and the terminal search engine, output a second set of fields, including at least a portion of the first set of fields, to an adjacent search engine.