Yes, they can affect performance by modifying the suspension geometry slightly that changes as the car travels through a turn. For example -- a wider stance will reduce the effectiveness of the front/rear sway bar slightly since the lever arm from it to the tire is longer, resulting in more body roll and causing a bit more tilting of the tires in the turns, which -may (or may not, depending on other suspension settings)- reduce grip when the car is pushed to the edge. In most cases though unless you are on a track it should not make much of a difference in handling, but you may see different tire wear patterns with and without spacers.Do spacers improve the handling or steering? Or are they mainly an aesthetic choice?
I have Garageline 15 front and 20 rear. I would do 20 all the way if I did it again. My non-stock wheels created stud clearance issues that required cutting the stock lugs down up front. 20 up front would have saved me from it. The look is actually pretty subtle. The car just looks 'right' rather than aggressive, IMO. But that's with my FordRacing rims. I think you have to look at each wheel set individually. The car really hunts during braking, and the spacers eased some of that. But there is a bit of loss in turning quickness. But the vast majority of time your car is on regular streets, right? So do what works there. I know if I didn't have to cut the lugs, taking the spacers off would just be like taking another set of wheels off. So for track days I would take them off.I have H&R Spacers on mine. I ran with 20mm front 25mm rear. It's really aggressive looking! If I had to do it all over again, I would have gone with 20mm all around.
So are you saying that a stiffer sway bar might be necessary to return the steering back to normal?a wider stance will reduce the effectiveness of the front/rear sway bar slightly since the lever arm from it to the tire is longer, resulting in more body roll and causing a bit more tilting of the tires in the turns,