15-20k on performance tyres is not unrealistic, less if you drive it hard. Pirelli are a very good tyre, I do about 50k a year, and when going through tyres, I find tyre life is at the expense of grip, so its a trade of really, harder longer wearing may not be as good in wet and dry,
The best ive found for grip are Yokohama, Michelin, best all round continental, best life Bridgestone, although I'm impressed with the Pirelli's on the mustang and as we don't drive it daily, not really worried about changing them out.
Worst tyres have been maxxis, great life but deadly in the wet.