Hi, I got my hands on an ebay sir wing replica. The spoiler is fiberglass. The spoiler has a lot of holes in it because of poor mold quality, but I can fix that with bondo.
However, the spoiler is for Jdm trunk, and mine is USDM.
Are there any tutorials how to modify/sculp the spoiler to fit USDM? I've seen images where the spoiler fits USDM.

 

SiR CH cars may have similar chassis bits, but is not the same body as USDM CG cars. You will have to modify your spoiler to work.