camber kit is probably a good option.
If u go to a tyre shop, make sure u get a 4 WHEEL THRUST ALIGNMENT! if u only get the fronts or rears, the toe will not be corrected to 0.
I have a cd5 with around a 3inch drop. my camber is between -2.5 and -3
as my wheel shop said, its the same amount of camber as mark skaife.

cb7 owner has a good point, this is what v8 supercars have.

onto camber kits, I didnt get one because my tyres were about 100-120 each.
I have 18inch wheels, and my tyres are 215/35/18. The sole reason i didnt get a camber kit was because-
1) too much money at the time
2) with low profile tyres (35) i thought it probably isnt worth it.
My solution-
flip your tyres making the inside edge the outside and the outside the inside when they get bad. I just did mine, can't really remember how many km's is suggested but it depends on ur amount of camber.
So basically im probably getting at least 80% of the wear from my tyres. which isnt bad considering a -2.5 to -3 inches.
i do take it to the extreme though and wait till they are pretty bald before i flip em, but it costs me like...$40 to flip all 4 so im not complaining.
Still thinking of getting a camber kit after my next set of tyres.