In fact, there are many kinds of modifications. Some people just need to add a tail/front bumper/side skirt to their appearance, so they won't spend much money. If the power/appearance is greatly changed, it's hard to say about ordinary modification, about 5~ 10W. If all the accessories you use are imported, it will cost hundreds of thousands. If you give a picture (to participate in the auto show), it should be at least 50W, but I suggest you go to a more formal refit factory. It's best not to buy cheap accessories for cheap results.