It does depend where you’re at with the car. IMO I won’t notice 10kg of weight off the body of an 800-900kg car, it’s only going to be genuinely useful when racing. Where I might really notice it is when reducing unsprung weight, which primarily means wheels and tyres.
It’s almost a fetish to get the new shiny lightweight bits for track cars and I totally get it, the amount I spunked on parts for my 182 was insane and I enjoyed every minute. Personally I now wish I’d done the basics and spent the rest on tuition and actual track days, which oddly enough was the advice a lot of more experienced people gave me at the time 😂
If you fancy doing the mods, can afford to do it without cutting back elsewhere and don’t need or don’t want the tuition then I’d say fill your boots and enjoy every minute of it. If it’s one or the other, personally now I’ve been there and done it, I’d spend the money on tuition.
At the end of the day it‘s just a hobby, do whatever makes you enjoy it 👍