Personally, I think putting R32 valance on GTI is blasphemy both towards GTI and towards R32. Towards GTI because it makes it look like R32, towards R32 because GTI can never imitate THAT sound, and I associate twin pipes with R32 sound.
Moreover, I am an adherent of Q-carness minimalism, in the sense that if I were to tune my GTI, I'd leave it looking stock (except for slightly lower suspension). I'd never put 4-pipe on the back, or do R32 thing. I'd leave my asymmetric two-pipe on a standard valance.