I bought this 1/2" spacer for a 2006 Nissan 350z, and after about an hour, it was installed. Upon starting my Z, it sounded more throatier, and when I took off, I immediately felt a difference in the acceleration, especially in the mid range. I am very well pleased with this product, and the instructions were very on point. Don't forget, buy some copper permatex, and put a good seal on top of the existing gasket before placing the spacer in. After placing two washers on each strut bolt, my strut bar went over my engine without touching my hood. This is the first of many upgrades.