Hi, here to answer your question:
1) Can i use this buffer on my front Sport Spring? (Currently my front is Sport Spring and rear is Stock Spring)
Sport spring would be using difference size instead of stock spring.
I hav to judge by a spring picture.
2) Will this increase my Wira height?...if it does, by how much?...
Yes it does increase but only 1 cm.
3) What happen when i installed the buffer higher or lower from the middle?...
Must be adjust and install on the middle,if not side effect will occur to make you hav a strange driving feeling.

Front and rear is RM 80 include postage.
Do you interest in it?
Thanks.

which over stiff situation causing by not balance install.
This buffer will not harm the spring in either long run or city run.
Instead it help protect from over compress when heavy load.