Hi folks, I'm trying to get my head round all these mods and kinda struggling a bit.

There seems to be a Kev mod, an o2 thing and what seems like various different filters.

So can someone explain them in plain english, and please don't send me links to Kevs page as I honestly can't make head not tail of it all.

Can someone also tell me how much these mods will cost me if I purchase them

Many thanks.