Have you tried cutting that chicane on Suzuka (
turn #16 (see map)). As you're coming down the back straight take the fast left-hander like normal but as you straighten out keep to the center/right of the track then brake earlier than you normally would for the chicane. Turn slightly to the right as if you're just doing laps on Suzuka West to cut the grass. Aim your truck towards the apex of Turn 17 and power out down Turn 18 towards the finish line.
I ran all the races with the Ram which had all power upgrades/weight reduction and untuned fixed suspensions. I power limited the Ram down to I think 455-460pp?
Suzuka was a hard one. I was cleared of the pylons by lap 3 and just went Tacoma hunting for the rest of the race. Just be very careful while turning in/out of corners. I found (at least for me) that if i clipped a tiny bit of grass I'll be drifting.
Wait.. I think said you're already doing this. Nevermind then. Have you tried taking the left hand sweeper after the back straight a bit wide to use the run off area? Not sure how much of a benefit that is though.