When you roll to a stop you do smell that rotten egg smell for sure, especially with your window down. The rasp is what drove me crazy!! I tried 3 different kinds including resonated and it would never go away. I finally gave up. You may want to check with Crawford because they were working on high flow cats.

http://www.crawfordzcar.com/html/performance_parts.html

 

It looks like Berk and Fast Intentions both have HFCs and Test Pipes. Berk's HFC doesnt throw a CEL. It looks like that's the way that i'm gonna go

 

Even the Berk HFCs are a little raspy/hissy when cold (radio off/hard accel ~3-5k rpm), so I'd imagine test pipes are very loud.

I got teh Berk HFC's and have no CEL, and they really improved the burble of the stock exhaust note.