I want to buy a downpipe for my 02' Regal GS. Is it worth the extra money to get it with 304 stainless steal? Also, could I pass emissions if I get the catless downpipe?

 

From a durability standpoint, it would be worth it to get the downpipe in stainless steel. As for emissions, it depends on how strict your regulations are. If you get a catless pipe, you can fool the PCM by installing an 02 simulator in the harness connector of the rear 02 sensor or have custom PCM tuning done. However, you would fail a "sniffer test" or any sort of visual. The downpipe in itself is a good mod for the supercharged 3.8s and provides a decent gain, the addition of a high-flow cat is not going to hurt the performance. I would just spend the extra and get the catted downpipe personally.