Y Pipe Interchange and Options

[rodrju]

Hello

Looking for some options to get rid of the dreaded two-cat Y-pipe on the 85 Diplomat. The cats are badly deteriorated and must go. Previous owner tried to JB weld them back together.

Sadly, searching for the Canadian y pipe yielded no stock. I suppose those have been gone for some time now…

Car has no longer has an emissions control equipment so I am looking to remove all cats-not repair or replace.

Does a y pipe from an earlier f-body Aspen/Volare interchange with the Diplomat?

If the current y pipe is removed can the cats be successfully hacked out and pipes welded in?

What is the next best bad option? I did not want headers….but I am open to the idea.

Thanks.

 

[Mikes5thAve]

Yes that's all that y-pipe is. The part you first mentioned.

 

[AMC Diplomat]

An hour at a muffler shop... boom done

 

[81ImpNC]

I replaced the exhaust system on my 81 Imperial which is the same setup as just about all the FNJY cars. My exhaust man gave me two options: 1) Run a tab while he recreates the factory setup with two pre-cats off the manifold and one main cat under the passenger seat or 2) Run two straight pipes back from the manifolds with a muffler for $400. I chose #2. It is slightly louder at certain points of travel but not noticeably slow and gives a nice exhaust note. The opened-up exhaust combined with running high test fuel and 14* BTC makes the car feel like it has an extra 10-15 HP.

 

[rodrju]

Update:

Got an F-body Y pipe from a 78 Volare 318–not sure if it was a 2 or 4 door.

An F-body Y-pipe is NOT the same as an M-body y-pipe. Close, but no cigar. The shop was able to modify it to work. It needed to be lengthened on the passenger side.

Also had them install an O2 bung so I can install an Air/fuel meter for tuning.