It will take a few hours for the video to be ready on YouTube, but I just did 26:27, here is the setup. It was a no stop, using higher fuel map for most of the lap, but going to fuel map 1 once I have traction out of the last hairpin, then back up to a higher map when I reached the flat part at the end of the straight. Map 6 in the early laps, then map 4 for the rest. Also some short shifting. If you don't want to bother with all that you can just leave it in map 4 all the way, maybe even map 3, and it should still be an easy win, but obviously the total race time will be slower.
As you haven't posted before, are you new to the game? You need to get a rear wing from GT Auto to use this setup, everything else is from the tuning shop. It doesn't have any other changes from GT Auto. Use ABS on the default setting, and I'm using a controller with it set to max sensitivity. I have also moved the MFD to the right stick to be able to mess about with fuel map so much.
The exit from the last hairpin is one of the hardest things to do well, it needs just the right amount of throttle to give it a little bit of oversteer, too much throttle can either make it slide and oversteer too much, or can cause it to understeer and push wide. You also have to set it up just right, slowing to a really low speed in just the right place on the track to start the gentle throttle slight oversteer bit. If you find it too tricky you can just use TC 1 and be a bit slower, not worrying about trying to get that perfect slight oversteer out of the car, you can still win really easily just cruising round that last hairpin.
I put the steering angle adapter on, but I don't think it matters, at least not when using a controller, I can't tell that it gives me any more turning ability at any point.
Another tip - I've now learned off by heart the fuel budget % for the end of each lap, you should have at the end of each lap:
1 91%
2 83%
3 75%
4 66%
5 58%
6 50%
7 42%
8 33%
9 25%
10 16%
11 8%
If you're ahead of budget you can shift at higher rpms and/or use a lower fuel map, if you're behind budget you can do the opposite to bring it back in line.
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Edit: Here's the video: