if you trade 13" steel wheels for 13" alloy wheels then theoretically they will be lighter and therefore the car will be faster.
however if you alter the overall diameter of your wheels + tires then the acceleration of your car will be decreased and your speedo will display a speed lower than you are actually doing.
Alloys will also improve the ride as they reduce the non suspended weight of the car. The effect of the weight loss is much more significant than it would seem as the wheel is a dynamic component. The effects will be better acceleration, better braking and a reduction in the forces having to be absorbed by the shocks and springs, etc.
Oh and they usually look good as well. [8D]
Dave.
Marea HLX 2.0 20v
<h6>FIATcentral window sticker, silver poppy coral, titanium tax disc. Blue Momo Tomahawk Gear Knob Blue gaiters, Blue sidelights, Blue interior lights, Blue lacquer on engine, feeling blue
Ecotek fitted, removed and waiting for warm weather
So much to do, so little time.... and Totally Skint!! </h6>