2 observations - do you actually need one for emissions/inspections and put it wherever the shop can fit it without causing clearance issues (maybe under the truck bed where there's some space). The early type of catalytic converter is obsolete (2 way converters) and CATs only work when your engine is running at it's optimum AFR. It's potentially an expensive component to add to an exhaust system. Are you going to run a bigger diameter exhaust to match the headers?