The best engine mods were done at the factory when they built
the turbo versions (and the internal changes were pretty extensive;
it was not a bolt-on turbo application). As a result, there is
practicly nill info on souping up the normally aspirated engines.
It is always cheaper (and more practical) to sell a normally
aspirated model and buy the equivalent with a turbo engine. As a
result, no real after-market goodies for the normally aspirated engines
and very little info on "megasquirting" them.