What files and lines in XML have you changed exactly so I can do myself without losing my new skins please.
Engine (ferrari):
<SplineElement x="0" y="0" op="=" />
<SplineElement x="69.9528" y="8226.552734375" op="=" />
<SplineElement x="121.655289" y="20830.13671875" op="=" />
<SplineElement x="176.0811" y="39225.109375" op="=" />
<SplineElement x="247.059937" y="70283.28125" op="=" />
<SplineElement x="326.8007" y="114366.359375" op="=" />
<SplineElement x="413.5384" y="172779.1875" op="=" />
<SplineElement x="514.7543" y="252490.359375" op="=" />
<SplineElement x="629.6146" y="335384.46875" op="=" />
<SplineElement x="759.6371" y="412833.90625" op="=" />
<SplineElement x="902.426758" y="492337.4375" op="=" />
<SplineElement x="995.594" y="544543.8125" op="=" />
<SplineElement x="1046.77869" y="565721.4375" op="=" />
<SplineElement x="1099.97632" y="581646" op="=" />
<SplineElement x="1203.06" y="580678.75" op="=" />
<SplineElement x="1230.45" y="575113.75" op="=" />
<SplineElement x="1308.21606" y="530524.5" op="=" />
<SplineElement x="1487.021" y="300000" op="=" />
<SplineElement x="1600" y="0" op="=" />
Chassis (ferrari):
<Chassis>
<Mass value="739" />
How to edit aerodynamic performance i don't know.