I've been running my plug and play HID kit for about a year now. The recommended fuse to use I believe is a 20 amp fuse but I left the one that came with the car which is a 15 amp fuse. Would using a 20 amp fuse have any effect on the lights brightness or what can changing the fuse affect?

 

Fuses help protect the harness in case of any surges. It is recommended to change the fuse when adding aftermarket HIDs on cars.

The reason being is when the ballasts first turn on, the voltages may be real high, but it settles down drawing less power than halogen bulbs. Sometimes the initial power on burn 15 amp fuses.