I add just the Rails, and it made a HUGE difference. I had already had an upgraded suspension, front tower brace and a roll bar and even then i noticed a huge difference. even had to remove my rear sway bar because it was so stiff afterwards..

 

I went to a much looser rear sway as well, though I imagine more of that is from the rollbar.

As far as the butterfly part, Mazda put it in it's new cars. It's for those "45*" situations. On turn in, the outer front tire will want to get closer to the inner rear - a brace to help with that natural flexing has to help.

 

Anyone know what gauge the fm rails are?

 

I'm pretty sure its either 16 or 14 gauge aluminum

 

Stainless steel, about 1/8" thick.

 

they dont look like they would be that hard to make, hmmmm

 

The butterfly looks barely welded at all from the pictures on FM's site. I wonder what some quality time with a MIG would do for them.

-Mike

 

Maybe my "butt chassis flex dyno" isn't very sensitive, but I couldn't tell any difference after installing the rails on my ~120k miles chassis.

 

No point in welding it anymore,the butterfly is stitch welded together.

 

high res version at http://abefm.smugmug.com/photos/55977906-O.jpg


high res version at http://abefm.smugmug.com/photos/55978324-O.jpg