Can you make a 94-95 cat fit on a 90-93 Miata by using the 94-95 pipe from the header collector to the cat?

 

no. flanges are different angles. you would need the matching year catback. or a custom exhaust

 

thats not correct. The catback is the same for all years between 90-97, I know because I put a 94 catback onto an otherwise stock 90. The difference is on the header/cat flange, which is angled differently. Read his question carefully, he is asking the right question. Now can the intermediate pipe between the header and the cat be swapped on to allow a 1.8 cat to fit? I really dont know the answer.

 

Nick, the cat can be used. The part between header and cat itself needs to correspond with the cat used.

Flyin' Miata : Tech: 1.8 conversion

 

Sweet.

So, for anyone searching in the future....
You can use a 1.6 header, 1.8 downpipe, and 1.8 cat OR a 1.8 header, 1.6 downpipe, and 1.6 cat. Both with a 90-97 catback exhaust.