On 09 sports there is a rear 17 mm antisway bar in addition to the 22 mm front where standard has only front 22 mm bar.
For 08's and prior deactivating the 21 mm front bar will improve handling and ride; reducing the huge understeer of those Fits is a great improvement..

 

i have yet to hear any noticeable rattling...at the same time some people were reporting noise from the rear license plate holder, where the dealer only puts 2 screws. Not sure if they're related, but they could be!! I only have 2 screws in mine but I have yet to notice it flapping when i'm going at higher speeds.

 

My rear license plate started to rattle at around 350 miles. I added 2 more screws and made sure it was tight. Now no more rattling sound from the back.

If you are like me who likes to stuff all nook and cranies w/ stuff you will likely hear rattles sometime in your car's life. re-arranging your stuff, or wrap them w/ cloth, or line the cubbies w/ felt will help.

 

I cant hear anything cuz Im too busy celebrating that it is less than 20 bucks to fill up!!!!!

 

^^^ i kno i was so proud of having a fit when it only costed me 15 bucks to fill it up, weekly ^.^

 

I was paying as much as $81 with my 08 Accord Coupe not too long ago. OMG.