Another thought... the composition of some pads may also contribute to squealing. What pads are you using?
That's true as well. This is a notorious sideffect of track pads, especially the ones that need to be warmed up for full effect. Those make lots of noise on the street, and consequently don't work too tell either due to the lack of heat.
BP 2005 330i ZHP / 6MT Imolarot / Naturbraun 2003 330iT / 6MT
Orientblau / Naturbraun
It's not the car you drive, it's how you drive it.