I want to go to mazda to get the warranty compresion test and I have a full exhaust including test pipe in place of cat. Does anyone know if that would void the warranty since I have no cat?

 

Yes it will. If you want a compression test done, you'll have to take it off and replace it with the stock one. And not just the cat/midpipe. The whole exhaust. They will find some way to screw you out of your warranty even if they can't prove that your aftermarket part caused a problem.

 

I would not worry about the aftermarket exhaust, but the midpipe I would for sure change out for a cat. If you have the stock cat and the stock exhaust hanging around then why not do both.

 

The best way is to keep or change it back to stock whenever your bringing it back for warranty work.

 

I've had 2 engines replaced under warranty with a different cat back exhaust on. Your on your own with a midpipe.