It is installed on my 1989 Chevy S10 with a 5.7 liter TBI small block from a 1992 C1500. Can't say it improves anything as I've only used it for air filter clearance above the manifold. Amusingly though, the box it comes in says in big bold letters "NO Whistle!" Well it doesn't whistle while driving, but as soon as you park the truck you will hear a very clear, almost high-quality WHISTLE with sound effect! Not really a problem, just found it funny as does everyone who hears it. They think I have a turbo or a supercharger.