I bought a couple of led stop tail bulbs to replace the crap normal bulbs that I have fitted at the moment, I have to open up the hole slightly for them to fit, the bulbs I got give out a white light and I will take a comparison picture to see how much difference there is
You shouldn't have to open out the hole.
This pic is of two LEDs. The first was a budget one that claimed to be the brightest on the planet and TBH I struggled to see the difference between that and stock.
The second cost a bit more but well worth the money. (Sorry I don't remember where or what)
Nothing is foolproof to a sufficiently talented fool.
The link is the bulbs I am thinking of getting.
The ones I got for the cage were about 2mm diameter too large to fit into the lens space.
I did try grinding the edge off but they broke before I got enough of the plastic removed.
I have for the moment fitted some bike specific halfords quick illuminate rear stop ta bulbs,they are supposed to light up faster and brighter than normal bulbs