It's probably the best Tsukuba I've seen and I love the Gran Turismo banners.
I can only give it four stars at the moment because the edges of the track are not smooth, and the kerbs are inaccurate. In reality the kerbs are placed behind the white line.
There is some good details in the track, such as the tyre marks on the road, but some of the models are low poly and give a dated PS2-era feel. Considering you said you converted it, I'm guessing you converted it from Gran Turismo 5 which had a very dated version of the track already.