Factory exhaust diameter

Hello all,

I recently bought a milltek downpipe for my mk2 tt-s, however I am fitting it onto the standard cat-back and need to buy a reducer but I am not certain of the factory cat-back diameter. Some say 63.5 while others say 60mm, anyone who can confirm?(assuming it's same size as s3, if some knows otherwise please tell)

Regards

 

If its same size as s3 then mine was 2.34mm if i remember rightly. I did same thing as you

 

Well it's definitely not 2.34mm lol.

I think the differences come from inside bore diameter and outside diameter. You need a reducer to go from the 3" (?) Milltek to then slide over the outside of the catback, which IIRC is 63.5mm.

 

I meant inch lol