The LE5 is built on the older Gen-II block, with changes made over time. For instance, the connecting rods were forged steel, now they're melted powder (sintered metal)--despite what the book says, the LE5 does not have forged internals. The crank is cast, connecting rods are actually really good for being sintered, and the pistons are hyperteutectic (awesome technology). With the foamy appearance of the engine block and porosity (voids), I made the conclusion they went to sintered metal for the engine block also--I was wrong and the casting is lost-foam--my bad, and thank you @Batshot for the correction:Yes sir the blocks are lost foam castings .... I believe he meant to say the stock rods are powdered metal forgings .....
Real engine builders (who are not me) have said the foam casting process has known shortcomings in the LE5's production history, mainly resulting in thin walls on occasion which blow out under normal use, resulting in coolant leakage. Putting a forced-induction system on an engine that hasn't been checked for defects (see the above quote) can result in rapid decompression of one or more engine cylinders (your engine blows up).The block is cast from aluminum using a lost foam process. For applications ranging from 400 to 800 hp, a production block that has been screened for cracks, high porosity, or other imperfections and re-sleeved with a high-quality aftermarket iron sleeve is acceptable. This block can be flat-decked for use with the production head gasket up to 600 hp or an after-market mutli-layer head gasket up to 800 hp. For applications above 800 hp, the GM Racing modified block XGH679 is used. While some of the features of this block are not necessary at horsepower levels between 800 hp and 1200 hp, the features increase block longevity at any power level.
It seems we got to the same result, but the correct way, which is important to understanding why things go wrong and how to minimize that from happening. Thank you again @Batshot for the correct information.