Mirrors also making trem slowly.. but ppls using it... a lot.
I can only think of one map that has a mirror. And it's not a default map.
So. If 'many ppls' know how do that, may be one of this legendary Guru can tell how he make it? =]
If someone had made it already they would have posted it. The problem is time. It is easy to add, but it takes lots of time and commitment. And most of us who could add it, are rather busy, or wouldn't be very commited to doing it.
If you want to add it, then go learn how to program and do it yourself, instead of asking one of us to tell you how to add it. If we could tell you how to add it, we would have done it ourselves and saved time.
And please try to use proper english. e.g. use "people" instead of "ppls", "Mirrors make trem run slower" instead of "Mirrors also making trem slowly" ("Mirrors also making trem slowly" implies that mirrors are helping to create trem, but they are doing it slowly.) etc.