Go thru your wiring & sockets first.My tail lights on the 810 are bright as is.Any brighter and people would think i have my brake lights on.This would be a really not good idea.
Dim lights are 99 out of a 100 times caused by corrosion and/or bad bulbs & connections.
The whole idea is that POR needs some "tooth".Something to bite on.Rust is great.But blasted metal or ground on metal will work also.Follow their "prep" instructions to the letter.