As mentioned its how you drive and how much TQ you got... my CL65 tore thru my PS2's but it had almost 800 lb/ft of TQ.
My 997TT has 12k miles and the PS2's are almost done. I think 10-15k is fair based on driving habits and TQ.
2016 BMW M5 Alpine White
2016 AMG GTS Edition 1 Selenite Grey
2015 Lamborghini Huracan Bianco Canpus (Matte OEM)
2015 Bentley GT3R Glacier White
2012 Mercedes Benz C63 AMG Black Series Obsidian Black