Nice one! Post a pic. Tuning it is not a waste of time. It doesn’t achieve higher peak power, but it increases the power thruout the rev range. So it will be faster than stock, but you can’t brag about having higher hp.
How many km/miles does it have and has it been carbon cleaned? That’s a start, because I can assure you it doesn’t have the stated 354hp that audi says. That is a rare thing with these V8. So first thing would be to try and get the engine as healthy as you can: carbon clean, new sparkplugs, new injectors, filters oils all that and then tune it.