It does state 3inch to stock exhaust on modern performance website, however trying to slip the MPx downpipe into stock 2.25in sleeve was just a little hard. i recommend buying a exhaust expander from harbor freight
Slipped right in no problems. Other then that, simple install.
I also recommend spraying it with PB N'laster and let it sit over night.
MPx Downpipe:
www.modernperformance.com/pro...
Exhaust Expander:
www.harborfreight.com/large-t...
PB B'laster:
www.oreillyauto.com/detail/b/...