For a decade, F1 cars had run with 3.0-litre naturally aspirated engines with all teams settling on a V10 layout by the end of the period; however, development had led to these engines producing between , and the cars reaching top speeds of (Jacques Villeneuve with Sauber-Ferrari) on the Monza circuit. Teams started to use exotic alloys in the late 1990s, leading to the FIA banning the use of exotic materials in engine construction, with only aluminium, titanium and iron alloys being allowed for the pistons, cylinders, connecting rods and crankshafts. The FIA has continually enforced material and design restrictions to limit power. Even with the restrictions, the V10s in the 2005 season were reputed to develop , power levels not seen since before the ban on turbo-charged engines in 1989.