The 9A1 engine as found in the Boxster, Cayman, and 911 Gen 2 models is a quantum leap in performance and quality over it's predecessor, with sizes ranging from 2.9 to 3.8 liters.
Starting with the heart of the engine, the crankcase or engine block is an excellent piece, cast from Alusil rather than the Lokasil process used in the Gen 1 M96 and M97 engine. Changes don't stop there - the open deck design was replaced with a closed deck similar in construction to the 4.5 and 4.8 liter Cayenne S engines.
Although vastly superior, there is always room for improvement. LN Engineering offers its Nickies sleeving and special JE Pistons for the DFI 9A1 engine for model year 2009 and later Porsche Boxster, Cayman, and 911 models, with displacements of up to 4.2 liters, as featured in the December 2013 issue of Porsche Panorama.