It helps stabilize your car in turns by not letting the body sway to different sides when in a turn. I would say they help, but i have also been told that it prevents the body from moving properly and can crack some mountsunder your hood. Dunno if thats true though. Nopi.com and streetbeat.com have them. The price ain´t too bad.
I´ve never heard mounts cracking under the hood after a strut bar being installed. The bars are designed specifically to sway a certain amount but not enough to cause the body and frame to twist and flex, which isn´t good.
As for the effect on driving, could you have been thinking of an anti-roll bar, 91scortgtboy, as opposed to a strut tower brace? I upgraded my rear anti-roll bar to a 1" version (the stock version on the 2nd generation GT was 3/4") and have seen no adverse effects. See my review under Parts Reviews.
On the other hand, I have indeed seen an Integra the top of whose fenders had dimples in them around the strut mounts. It was hard to say whether his strut tower braces were the cause because he also had the springs slammed down low. I think his real problem was choosing inappropriate springs (too low) and struts (not enough damping) though the STBs may have made this problem worse.
As for strut tower braces, I´m thinking of getting a pair as well, though I am not expecting as much of an impact on handling as my anti-roll bar -- on the street at least.
Rob, you still have to take me for a ride in the Purple People Eater...
Strut bars should have no adverse effects if properly installed. By this, I mean using a good quality component with good fasteners. If tightened right, and evenly, they should only reinforce the area, not harm it.
If it causes any damage, it has been used wrong. In my experience with the 5.0 Mustang set, the STB will only improve the car.
strut bars keep the suspension parts from swaying side to side in corners. you should get upper and lower tie bars to get the full effect. I have also heard of the problem with extra stress. I´m sure it adds extra stress to other components however.... I´ve never actually heard of any of the road racing or autocross guys have the smallest problem with it over the years so I can´t see how it would hurt a street car.