Goes at the front of the axle-back exhaust section of many late model Subarus, including 2002-07 WRX and STI, turbo Forester, turbo Legacy, and more.
About 3.25" wide, 4.75" long. 3.75" center-to-center on the bolt holes. Just under 2.5" hole size.
Also applies to the axleback on the BRZ and FR-S