Lean manufacturing and management techniques as well as strategic acquisitions continue to give suppliers improved quarterly sales and earnings in the face of everdemanding customer price pressure. Gentex Corp. checks in with $39 million in second-quarter sales (up $26 million from last year) and earnings of $7.2 million, up 81% from a year ago.Corp. has $2 billion in sales and $91.5 million in earnings, up slightly from last year. ITT Automotive nets $102 million on $1.45 billion in sales during the quarter. Johnson Controls Inc. tallies $2.7 billion in sales and $69.3 million for the period, compared with $2.1 billion and $55.3 million a year ago. Corp. reports sales of $1.6 billion (up from $1.1 billion last year) and $50 million in earnings (up from $29 million in '95) in the second quarter of 1996, but that does not include results of the recently acquired Masland Div.