Necessary or not? And is Mazdatrix the cheapest place to get new ones?

 

I did on my FD. Made a minor difference decreasing noises from the suspension.

 

I would check the fronts, being as they have a bearing, that they don't bind. I replaced the fronts on mine when I did shocks and springs. The rears are nothing special, I just sanded and painted them. I also got the front strut mounts at an auto parts store (don't remember which one) for about $50 each.

 

check everything and be sure that it is installed properly and correctly. you can check ebay or parts stores.. there are lots of suspension parts like struts, mazda strut bar, strut mount, etc. that are available in the market, you'll have no difficulty in finding one. good luck