With the exception of the early Mk1 chassis catalytic convertors, the factory installed cats are quite good performers.  The large, monolith style ceramic cores used by VW flow about as well as ceramic cats can be expected to flow.  Beware of some aftermarket catalytic convertors, for they may actually restrict flow when compared to stock!

Autotech's line of replacement catalytic convertors are made with premium materials and entirely in the USA by exhaust manufacturer Magnaflow/Car Sound.  Power is maximized with these high flow convertors.  Exhaust flow is as good as or better than original VW parts on every application, while costing only a fraction of an original equipment convertor.  5 year/50,000 mile Limited Warranty.