I needed to replace my cat and resonator on my 2002 Pontiac Bonneville SSEi (L67). I wasn't looking for a downpipe until I found the ZZP downpipe with flex tube, and catalytic convertor already included. This complete downpipe was less expensive than purchasing a comparable catalytic convertor alone. The downstream O2 **** was 2 inches off (closer to the engine) from the stock pipe since this product is more streamlined and isn't as long (or bulky) as the stock pipe. But repositioning the O2 sensor was not difficult. No problems with mating the ZZP pipe with the manifold ****** (it was nice to have another pair of hands and eyes helping from the engine bay while I was under the car). I also installed the ZZP 20-inch universal resonator to replace my stock resonator. When idling, the car still sounds as it did before but, when revving the engine (along with my in-fender cold air intake), there is a noticeable increase in growl/purr (in a good way!) of the car's original sound - and this is with the stock mufflers currently in place (which will soon be upgraded). If you need to replace your catalytic convertor I would highly recommend this downpipe AND a ZZP resonator (all stainless steel!!). The photo compares the stock downpipe, cat, and resonator to the ZZP H-Body downpipe and resonator side-by-side.
