http://www.autotrader.co.uk/EDITORIA...ent/34434.html

"A top tuning company has built one of the world’s most powerful topless cars – a 910bhp Porsche 911 Turbo Cabriolet.

9ff has increased the standard 911 turbo engine from 3.6-litre to 4-litres and fitted two turbochargers boosting power by 430bhp."