Actually Ferrari's 'flexi-floor' was was within the rules of interpretation but once it was deemed an unfair advantage it was banned, it was not a deliberate breaking of the rules.
I'm quite sure that it was less rigid than the regulations allow. In addition, it was actually designed to deceive the FIA tests on rigidity - when the stress was applied in the test, a spring prevented it from moving more than it was allowed. However, the greater forces generated by racing at speed meant that it could flex a lot more than it was allowed to as defined by the regulations.
Thank you again for that sensible post. I think the tifosi need to come down from their ivory towers and read up their facts.

Ayrton Senna: WDC 1988,
1989, 1990, 1991
McLaren: WCC 1974, 1984, 1985, 1988, 1989, 1990, 1991, 1998,
1999, 2007McLaren: WDC 1974, 1976, 1984, 1985, 1986, 1988, 1989, 1990, 1991, 1998, 1999, 2008