Brian writes: Sajeev, I have two V-8–powered vehicles that both need one catalytic converter replaced. The first is a 2005 Grand Cherokee with the 5.7-liter Hemi, and it needs the right-side cat ...

Modern vehicles and the internal combustion engines that power them — well, most of them, that is — have come a long way in recent decades. From inefficient carburetor systems to fuel injection and, ...