Hello.
These strut bars are mainly for a Tezza, on an IS they will probably resonate on your airbox, unless you modify the bar.
I have front and rear strut braces, mainly for looks, however when there off you can feel a slight difference, mainly in steering but it isn't much.
As far as i'm aware ARB's are the way to go if you want to feel an improvement.
This is just my oppinion, I'm sure others will be about soon.
Aaron