help me o find a part!!

hi !! im driving k3 hatch in korea.
We only have lower trim, and only few hatch is sold. so we don have any tune part or exterior parts.
even front bumper was sedan's part, so i changed this to koup turbo's carboned one.

im actually want to change muffler and diffuser to twin.
in korea, there is no any different other part. so i think i need order from states or other country.

any body can help me to find out a name or number of parts?

this part of back what i want... how u guys order this?