KoRn_Dowwg666 isn't currently here, so I'll help ya out.
No prob, I used a Ford GT. If you don't have this car, it's gonna burn a hole through your wallet, so don't do it if you can't afford upgrades. Give it the race package on EVERYTHING including the supercharger and I garuntee you'll smoke everyone in the game. Now, how you customize it is unique to you, so I won't waste your time with HOW to trick it out, because you may not like my settings, but race packages are vital. All I will say as far as customization is screw Top Speed and max out Acceleration. Acceleration is ten times more important than top speed. Odds are you'll never live to see the top speed because the meter never stops unless you turn. I've made it to 455mph before I stopped, or did I crash? Whatever, in any case, top speed doesn't really matter. Just practice with it and smoke the ***.
I'm not gonna say it's a cake walk either. Just because your car is badass doesn't mean you're badass using it. I myself have only mastered the Ford GT and Skyline.
Now if you want to stick with your Gillardo, no prob either. My memory is a bit foggy, but if it's an upper echelon teir 3, you're good. Crank up the acceleration and such and smoke him. The thing about Darius is you have to prepare your car almost exclusivly. Make sure, no matter what car you use, it suits you. If the accel. throws you off, adjust you car accordingly. Race packages highly recommended, so go do some other races if you need cash.
Now the trick I used with the Ford GT, keep pounding R2. This'll speed up your acceleration, normally you should have your brakes adjusted on front brakes so your car will turn much more easily at high speeds. This will also help you immensly when you're pulling out of a crash, but this is not permission to go crash, because it won't always save you, so keep crashing to a minimum. By tapping R1 as you turn, your car will slow down, but your turning will be much better, and with a fast car you'll bridge the lost space in no time.
Your Gillardo should do the job... assuming it's an exotic, it might be... I don't remember. But genually, muscles are difficult to use on turns. Carbon Canyon is littered with them. Not recommended. Tuners make up for it, but you won't be able to keep up with Darius if you screw up. Exotics are your best bet.
In case your settings don't help heres what I do.
max accel.
max horsepower
max drift
all power on front brakes
max oversteer
Normally to drift you should have it on max torque, but not for this race, somehow it works.
If my advice don't help... ask KoRn, he probably knows the game better than I do. I only borrowed it from a friend.
Iron Chef...