I've managed to get up to 22, not sure how you've managed those extra MPH... You got some kind of trick?
Oops, meant to edit my last post.
I'll upload my tune tonight to see if it makes a difference, If I remember rightly I'm running with zero camber on the front, a little bit of positive on the rear plus a tiny bit of toe out on the rear. Suspension is all stiffened a little bit, max aero on the front, minimum on the rear. Some tweaked diff settings with I think a balance of 90% to the rear.
There seems to be a sweet spot when you gently move the analog stick, it turns in very fast with tonnes of grip, If you go full whack on the initial turn in then it will just squeal and lose speed. If you can turn in gently at the beginning of a corner then you can gradually increase the amount as you go through and it still stays very grippy. I've basically tried to take a line through the corners where I can turn as gently as possible for as long as possible.
So on my video if you slow it down:
0.06 - I turn in gently as I pass the sign on the right
0.08 - Gently turn in to the right, trying to go as wide as possible (I actually turn in too early in the video and don't go as wide as I can).
0.11 - Gently turn to the right just as I pass the the sign on the left, gradually increasing the amount on the analog stick to try and use as much of the road as possible. Because I turned in too early the in previous corner I'm not wide enough in the video and end up turning in early again, slightly clipping the grass/curb on the way around.