I gave the Impreza a quick whirl just now. Not sure how I managed to pull it off:
148.2 mph (OTP, BNP, LCP, ABP, LGP)
When I first ran this, I'd go through the buried pipe in the construction area. This time I didn't so I wouldn't get the little jump right after.
This time, instead of going the big long way around the first split in the freeway.
After that I went on the oncoming side, switched back to my side of the road, drifted the next wide left bend, drifted the right bend to the straight away, switched to oncoming, boosted, back to my side, took the last ramp, landed in the dirt, bounced, and rode the wall on the last turn.
Yes you'll have to ride the wall on those dumb highway exits. It's like Criterion didn't care the slightest if anyone would bother making that turn without touching the walls.