We have Vararam intakes on both the C5 and the C6. They do work really good. The plus side is they do make a noticable difference in power. The downside is that the car takes a little while to adjust to the increase in air flow, you may notice some engine surg at low rpm's. It's a pain in the ass to install, also your engine bay will attract a lot more dirt, dust etc due to the hole you have to cut in your shroud.