2.8/S4 wheel wells the same?

[karmad]

And are they thicker then the 1.8t?

[kingtr]

Wheel wells thicker? The actual material? The S4's wheel well liner is vented on both sides (for the dual SMICs). Some people choose to put an S4 driver's side liner on their A4s to aid in air flow past the stock intercooler (drivers side only).

[Siena]

If you mean the actual wells (steel) then no, they're the same.