Hello @Thanush22,
u can do anything with Save Editing that is already in the base Game or any DLC´s, a 1000hp Engine like u mentioned is a Modifikation (Mod) and will not work with TruckersMP as it is not Supported by TMP.
Also here is a list of the current Supported Mods by TruckersMP.
Hopefully that will help u, with ur Question about the Mod.
Kind Regards,
Tim