DO IT. The thicker rear will help decrease the excessive understeer of the car. Yep, the stock one 16mm and the TL/CL-S bar is 19mm. I have the Type S rear bar with the stock I4 front, and it made a nice difference. It was hard for me to isolate exactly the difference since I put the rear bar on at the same time I put on Koni adjustable shocks, but I know a lot of guys put on the rear bar alone and felt a nice difference.

Plus it's only ~$50 and easy to install (provided your endlink nuts aren't too rusted ) Just make sure you get the Type S brackets and bushings to accomodate the rear bar. My total bill was like $65 from my local dealer's parts dept.

EDIT: At first I thought you said you did the front sway...now I see it was front strut bar...do it.