3" to 2.5" adapter question

Dumb question but, I'm getting a 3” bosal v1.5 exhaust to use with the factory 2.5” downpipe, can I simply use one of the 3”DP to 2.5” cat-back adapters flipped backwards from fredbeans? Not having taken apart the exhaust yet, I wasn’t sure if the adapter is directional. Is the collared side of the adapter 3” and supposed to go in the downpipe?

THIS is the adapter I was looking at.

You don't need one unless the neck down on the bosal has been removed.

From what I understand, the current owner has the bosal bolted up to an aftermarket DP with no adapter, which makes me think the necked down portion was removed (he is the 2nd owner so it came this way). So I'd like to have the correct adapter incase I need it. Will the above work in the opposite direction (2.5"DP to 3"CBE) or is it directional?

Called around a few places and the above 3"dp to 2.5"cbe will not work in the opposite direction. Anyone know of any places that sell an adapter to go the other way?

You don't need an adapter. You can use the donut gasket/spring bolts with the Bosal. It necks down.

Ask the seller to send you a picture of the neck. If it tapers down, it'll bolt up fine with the donut. If he had the neck cut off and a 3" flat flange welded on, you'll need to figure something out.

Thanks guys I have a thick flat gasket to make work for now. If that doesn't do it, found that avo sells the adapter to go 2.5"dp to 3" exhaust if anyone else needs the info. Let's you use the donut gasket to.