Trim from other VAG models

[MrP]

as alot of VAG models seems to share parts, will the a pillar trims from any other models fit a 5dr mk5 golf?

reason for asking is that i noticed that a polo has its tweeter mounted on the a pillar, and if there another model that has the tweeter there that would fit on a golf it would save me alot of time when i come to put my stereo in.

thanks