Yay, I wasted half a day today and still haven't score the gold
I almost throw my DS3 outside my window
even though I already watch the YT video dozen times
HELPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP!!!!!!!!!!!!!!!!!!!!!!
The only advice I can give you is practices, which admittedly is not what you want to hear after spending half a day on it.
I got gold on my second attempt, however, it would have taken me hours if I hadn't already had practice of TT'ing it from GT5 prologue. It's hard to be shown how to be fast at that track, its better to keep grinding away, and eventually you will find the time.
The best advice I can give other than practice, is to get rid of all driver aids except abs, as they will only slow you down. Mild oversteer in some of the low speed corners help pivot the car quicker, but makes sure that oversteer is under control before you try to accelerate away from the apex. Take the shortest line possible through the hairpins, even being a foot away from the apex is worth a tenth or two per corner.
For the first corner you can use the tarmac that leads to the pits to start braking from and achieve a wider line, braking diagonally towards the apex will give you a few extra feet to stop the car, allowing you to brake a tenth later, once at the apex, pin the car to the inside kerb, taking a bit of kerb will actually help turn the front in and eliminate any under steer. Be very tentative on the throttle, you can't afford to run wide as it will ruin your next corner. Don't pin the throttle until you can drive a straight line from the inside of the first corner to the inside of the second corner. Hug the inside kerb of the second corner as you did the first, don't even think about accelerating until you are absolutely certain you won't have to lift while exiting the corner, doing so will loose more vital tenths.
For the 3rd corner use the full width of the track on enter, trail braking until you are once again hugging the inside of the corner, and again, don't accelerate until you can drive a straight line to the inside of the next corner.
For the 4th corner, don't worry about drifting wide for a later apex, the gradient of the corner will assist you in this respect, you will loose time if you don't try and take the shortest line. Avoid taking too much grass on the exit of this corner.
After the straight, hard braking and a very late apex will ensure a good exit for turn 5.
Turn 6 after the tunnel requires the slightest of lift and then balancing the car via the throttle, this is easily the hardest part of the lap in terms of car control, as the car needs to be balanced for turn 7, a high speed corner in which mistakes are very costly, try and hug the apex but avoid lifting, the car will under steer wide, so make sure to not hit the outside barrier.
The final turn is perhaps the most complex, and hard to describe in words, so I won't try, just ensure you brake late and also allow yourself a late apex for the run to the finish line.
So remember, shortest line in the hairpins, late apex's for the corners with long straights following, and attack the section after the tunnel but try and be as smooth as possible or you will crash.
I tried to lower the TC and it even got worse since the 8C is tail happy especially when you try to tackle the corner after coming out from the tunnel 
for this one (since wednesday afternoon)...and I was like....ARGGGHHHH...and then I just ignore it today, hoping I'll be lucky tomorrow...
