it is going to be quite amusing bringing back a thread so old, but i came across it from some photography forum where an idiot was arguing that the supra wing was cosmetic only and the car did not travel fast enough to produce any sort of downforce, ect ect.
edit on what i said earlier, as i said it slightly wrong, i meant to say that the hp required to over come the drag on a vehicle goes up with a cube of the vehicles speed.
The interesting thing, is I doubt you will find numbers for the RMM or Veilside wings. And even if they are higher than the stock wing, you will effect the balance of the car without adding more front downforce.
Of course I guess if you lower your car, you have added more front downforce, so you need to change your rear wing.
Don't you know we drive the Toyota engineers crazy when we start messing with things.
If I recall correctly, when SW was running the Texas Mile a year or two ago he originally had the TRD/RMM wing on back but the car felt unstable, so when they switched to the stock wing they reported much better high speed stability. Of course, as Steve points out above, the overall balance of the car comes into play so as far as we know this conclusion only applies to SW's setup.