so i bought my megan catback w/ hi flo cat off craigslist for 100 bucks.. thought it was a great deal, it alsco came with a megan o2 housing for an extra 20.. so ive had my o2 housing sitting around for a while untill i got the DP.. so since my entire exhaust is megan, i ordered a megan 3" DP..

well it seems like the outlet on the o2 housing is only 2.5 ish inches.. and the DP inlet is 3.... uhh... wtf??? does the big ring thing( idk what its called that goes in the dp) make it addapt??

 

Its called a donut gasket and yes you need one.

 

yeah its the donut gasket from the stock o2 housing and downpipe

 

will it work? or do i need a new one?

 

you can reuse the old or get a new one. its only $15 at dealership

 

well i dont have many miles.. ill just use my stock one... i just got my dp in and held my o2 up too it and was like wtf?