Exhaust Pipe Size? - Between Cat and Resonator

O'reilly's and Autozone both sell U-bolts set for 42.5 mm. Those were the perfect size for the smaller union.

My aftermarket cat came with 2" pipes, so I bought an assortment of 2" reducers, including two that each said 1 5/8" (but were slightly different sizes). I ended up using the larger of the 2" to 1.625" reducers.

 

Came here for a simple answer, and in true PriusChat fashion, posters made a simple measurement unnecessarily complicated.

Posters making unnecessary comments, people measuring the wrong generation vehicle, flipping between imperial and metric...

Y'all need to go outside and socialize. Sometimes this forum is a little too full of itself.

 

I purchased eBay item 193690871378 in August 2023. Its outlet side has an ID of 46.4mm (a hair under 1 7/8"). The pipe between my old cat and resonator, which I expected my new part to fit around, has an OD of 42.5mm, in theory leaving 4mm of slop.

Before I knew about the slop, I had planned to cut, replace, and then drive to a local exhaust shop to weld the edge of my new part around the old one. Now, I'm thinking that it'd be better to have them do the replacement, as they probably have, or can make, a fitting to mate 46.4mm ID to 42.5mm OD.