All 32V engines have the same catalytic coverters. It's a direct bolt on. As far as I know, all 16V engines need modifications to the passenger side of a 32V converter pipe to make it fit. It needs to be extended about an 1 inch or around 2.5cm.

 

Depends on whether or not you utilize 32V headers.

If 16 V, I thought it bolted up but downpipes need to be heated at cat entry and bent a bit for width adjustment. IMO suggests an inch spacer or so.

If 32V tubulars, then you definitely need a couple inches of spacer. Slice off flange leaving 3/8 inch or so of tube on it, weld in a piece of SAE tubing. Again, heat pipes cherry red at cat and bend a bit to adjust width.

A 16V air pipe system will align with the 32V muffler air pipe and they bolt right up.

I thought the early 32V cat discharge pipes were different than S4. Are you sure IMO?
The 86.5 32V cat discharge looks same as S4.

 

Good to know.. early "Euro" 928S (80-86) all have dual exhaust, so I'm guessing they're the same size pipes aft of the cat. I'll have to measure a local early car to see - a very nice '86 16V came up for sale recently in NZ I was tempted by, but the emissions question held me off and it sold.

(86 is first year here in Oz which would require cats - which is why Australia for the S3 motor with cats in '86. I'd just prefer a 16V '86 instead for a change after owning a string of S4's).

 

The 16V is just plain enjoyable.

 

I'm 100% positive that an S4 cat is the same as an 85 32V. The difference is after the catalytic section. Past the connection.

 

You are correct.