Janspeed or Forge alloy intercooler pipes
Silicon TIK pipe.
Fit a sports exhaust with a sports cat
You can also buy uprated turbo's.
Don't be tempted to fit a BOV! They don't work on these engines & if anything you will loose power.
Don't bother with Speedboosters, they don't work either.
Another popular mod when cars have been remaped is to fit an Audi fuel regulator it's a straight forward & fairly inexpensive swap.
The engines come with an oil cooler as standard but some people do upgrade them, though I don't see the point my self. Brabus cars also have a more frequent service intervals, so if you do tune your car it would pay dividends to have serviced using the same recomendations. On my own car I used to changed the oil every 6000 miles. If memory serves me right the Brabus cars also run a slightly different cam so you can fit those. There also other Brabus bits you can plunder too, such as dampers & some very nice mono bloc wheels etc.
Looks wise your spoilt for choice! You can buy a lambo door kit for the Roadster & the is a massive choice of interior styling parts to choose from full leather interiors to alloy dash parts. There also Roadster body kits available too.