I would say that they dont pull. I think most girls dont even know that its GTI, its just a Golf in their eyes (obviously you get a few that are clued up with cars

)
e.g. i know a girl that said to a guy "Oh, nice Audi TT you have there"
.......................he didn't have a TT - he had an R8...!!
I think if you have a car that girls actually would like for themselves then thats whats going to make you pull, i.e. a TT, Z4, SLK, MINI. But then, you sacrifice being called g*y or hairdressers by blokes I guess...