So what is a diffuser actually? I haven't got a grasp of it yet.
AERO UPDATES FOR SEASON 1
Ok now I know the difference between diffusers and carnards after searching on Google Images. At the same time, I also did a search on the GTP forums on front aero kits. As far as I can see, there isn't any solid evidence 'within' GTPlanet that says that front aero kits does anything. If it does, it is minute.
If you think and believe that aero parts will give you an advantage, then I suggest you use a premium car. That's all I will say. In saying that, all Aero parts for Season 1 will be eligible. If you want to see which cars have aero parts other than Rear Wings, look at this
thread.
There maybe exceptions, since I came across some comments saying that adding front aero will put a permenant downforce value in the front downforce which can only be seen when a Rear wing is installed. So we'll slowly work that list out.
BALLAST UPDATES FOR SEASON 1
Ballast use for Season 1 is set at 5% of car weight...
For example if the MR2 G-Limited '97 weight is 1220kg,
the max amount of ballast you can use is:
1220 x 5% = 61kg.
And if you use weight reduction,
so full weight reduction for the MR2 is 1039kg,
1039kg x 5% = 51.95kg ~ 52kg.
So use the default weight of the car x 5% is the max value you can use for the ballast.