March Rocker Cover/Brakes

[Finto_GX]

Hi,
Reading away there, i learned that a march plastic rocker cover is better to have than a metal one as it doesnt give off heat as much? and its better for when you have a cone filter.

Can anyone clear this up for me?

And reading away again i learned that sunny gti brakes i think are bigger, are these a straight fit?

thanks in advance