amazed

Just sat down and realised how well engineered these cars are. slight overkill with some tech in my opinion.But still amazing. Just about got everything i need apart from idea for colours,so all's good. But i could do with more knowledge on the na gearbox.Which i'm putting in my tt. Along with diff and rear sub frame. As i believe from past experience ,although not on these cars, that......the diameter of clutch and fly wheel is designed initially to suit the gear ratios and diff. Which is set up for the weight of the vehicle and speeds it's made for. So the point or question i have is that for gains in acceleration or aggression then the na gearbox etc, should be the right choice. ???? if anyone makes sense of this then please send their opinion as a mass of knowledge truly is power. thanks Lee.