Imo i think a Audi R10/Porsche 917 is abit too much, Cause there is really no point in them being in TDU cause firstly you never see them cruising on the streets. Aswell TDU is no where close to a simulation.
Just to add from my perspective on modding, for both cars you would need a car that is really low otherwise the interior view would be higher then the main car aswell as other views would most likely be crap. Then you have your textures.. And if too big or use the incorrect .dds settings it can all go crappy on you. You also have the main interior file, the main interior file well lets just say if you were to actually make the car you would need to create the interior and i can say for sure that if its low poly it will really badly reflect like no tomorrow. Same goes with the body of the car if you have polys just put all over the place and not correctly laid out TDU will make it look crap.
From what i hear from basbas it takes 2 months (in spare time) to create a proper detailed model with textures.
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With 'the red box' pointing out the many requests i do have to admit this is why i ignore requests, cause its always up to the modder in the end anyway.