The CX-5 comes with an exhaust from the factory. So I'm not sure what you're saying. I was wondering what he hoped to gain with an exhaust made for a Mazda3.
LOL! Here we go again!
The exhaust systems on modern cars are not restrictive enough to reduce fuel economy. In fact, you will get lower fuel economy and worse throttle response if you change the back pressure characteristics and natural resonance frequencies of the stock exhaust without figuring how to correct the fueling. The engine is not designed to automatically adjust for a header or exhaust pipe with different characteristics - that's why your car will run worse, not better, after such a change. This is especially true in a car like the CX-5 which has a highly tuned header and exhaust system - all the operational thresholds and the tuning is designed for the characteristics of the system at various rpm's and throttle openings. Good luck finding anyone who knows how to make everything as good as it was with the standard exhaust.
I laugh at the "ricers" who pull away from the gas station with their new Honda (or insert make of your choice here) with the exhaust sounding louder and faster than a herd of wild buffaloes but the car going nowhere fast. More gutless than the stock car, many of them would have a hard time outrunning a herd of buffalo! But they have spent thousands of dollars absolutely ruining the throttle response and acceleration of their almost brand new car! Oh, and their fuel economy. They have wasted so much money that they can't even admit it to themselves that they made their car slower than ever. At least it sounds "cool" to their friends. I have to think these people have smaller than average penises. Or maybe just their brain.
But to answer your question, I was simply curious what he hoped to gain with an exhaust made for a Mazda 3. It's his car, I don't care if he wastes his money making it run worse. People do it all the time.
