I just installed a fsport rear sway on my 07 350 but I realized after install tapper was upside down but the bar fit does it make a difference if the sway bar is upside down or not at all also I have the afs light now blinking in my dash how do I fix this as well

 

So the actual bar itself was mounted upside down? From the pics I see online, the bar appears to be a "flat-plane" style bar. So either way, it should work the same. But I'm so OCD, I'd have to fix that! LOL

 

You'll have to get back under the car and fix the AFS sensor to get rid of the light. IIRC, the sensor is loosened when you remove the sway bar links from the sway bar. There's a little black bar on it that should be in a horizontal (neutral) position. I can absolutely guarantee it's probably not in that position. I want to say its on the drivers side.

https://www.clublexus.com/forums/att..._bracket_1.jpg

Sway bar orientation shouldn't matter unless you received one that had the drop in it for cars with the full size spare (which were overseas only, e.g. Australia)