Its not bad, but its still the TT.

I want that powertrain in a Sirocco, which is possible since its based off the same platform as the Golf as is the TT.

Maybe you didn't hear me the first time, its based off the Golf platform.

Audi TT
97.2" wheelbase
164.5" long
72.5" wide

G37c
112.2" wheelbase
183.1" long
71.8" wide

Even though its wider, it has 0.5" less shoulder room than the G, but the Golf is pretty roomy in terms of shoulder room.  I've sat in them and they're fairly roomy for the overall small size.  I have not sat in a TT though.