It just devalues the car, and most people other than the owner and his rose tinted specs think it looks ****.
It's the same old crap;
Tint the windows illegally - so they can't see out.
Smoke the lights illegally - so nobody can see the car at night.
"Stance" the wheels - with negative camber so you've actually got the contact area of a bicycle.
Lower it - so it won't go over speed bumps anymore, but they're convinced they can corner 20% faster than before.
Daft alloys - that cost more than the car, and probably rub at full lock. Unless you use -
Wheel spacers - so that all the bushes are put under more stress, wear faster and put the wheel geometry out.
Painting the logos black - because chrome is so 'conformist' .
Barry boys bodykit - Why didn't Mercedes think of that bit of body styling genius?
Mudflaps - 'cos racecar.
Blue sidelights - so other motorists see the flash of blue in their mirrors and start planning to pull over before they realise it's just some pillock in a Corsa.
And generally just bolt as much tat onto it when they get bored and have money burning a hole in their pockets, each time thinking they're making it look better and better until it's almost completely worthless.
(I know you've not gone to these extremes, and you're mainly about the alloys, but hay hoo).
We tend to leave it to companies like AMG, Brabus, etc who can be subjective, take time and consideration, prototype and refine to make something that genuinely looks good, yet more outrageous than the standard model. Cheap sub 1k cars are often modified in all the ways I mentioned above, by young drivers who it's their first car and they're eager to tinker with it and try to make it look cooler because it's all they can afford at that age.
It's up to you what you do with your car, and if you like it then fine, but you asked for opinions on modifying in the UK and that's mine.
^ Look how unique I am! Unlike all the others on the road. (I wonder why?)
TLDR; I'm not a fan.
