So, with my hacked up, dented 2 in dual ANSA exhaust not suiting me, I want to explore some options. I have no cat right now, but I want to incorporate a modular cat so I can get regular IL plates after the shark *passes* emissions, which is only a idle sniff for me. Also, I want to get rid of my current dual because the flanges that bolt up to my MSDS headers are so bent and rusted getting them to seal is close to impossible.

In the picture below are my ideas for how to incorporate the cat(s). Should I go with the dual cats and then the Y or go with the Y and then the cat? My reasoning is having the Y after the dual cats makes the cats closer to the engine allowing them to heat up more and faster, equalling better chance of passing sniffer. Also, wouldnt having two cats even more increase my chance of passing sniffer? I alread have the two 3" cats, If I dont use them both I can keep the other one as a spare.

One reason why I want to go with the single exhaust, is wouldnt it be silly to have the Y so far away from the headers if I go modular with the cats and swap them for straight pipes.

One final question would be what brand of muffler should I use? I am hoping that changing to a single 3" will make my car sound more Euro, like a higher pitch sounding exhaust, kinda like the 928 sounded in Risky Business. (I know that was not a real 928 exhaust note). What type of muffler do you guys recommend to help me achieve that? I was thinking of using just a single Moroso muffler. The whole system will be 3".

 

If I had the time, money, and two cats, I'd run duals like an 86 Euro/ROW or 86.5 US. Put an X after the headers, then dual cats, then dual exhaust to mufflers next to the tranny, and so on. That's what I intended to do with mine, but didn't have the money when I needed the exhaust done. Right now I have headers to a Y to 3" single to a 3" center/center 4x9x14 Magnaflow and out the back. It sounds very euro/racecar and is loud. I used to have the current Y to a 3" catco cat to a single Ansa system. It sounded good, but completely choked the car. It had a constant low frequency note and wasn't nearly as raspy as the current exhaust.

I don't know if this is universally true or if it's just the cars I've noticed... If the muffling is further forward, it has a lower pitch and is louder at idle. If the muffling is further back, the sound is more euro-ish and louder at higher revs.

 

Thanks, Matt. I think I am in the same situation that you were, my exhaust right sucks, and I dont have much money to play with and want it done. Therefore the single 3" pipe.

 

I've heard that two cats always flow better than one. If you have the funds, go with the dual. It will also decrease your emmisions.

Most of the sound of the 928 in Risky Business was from a Ferrari and not a 928! It will be near impossible to make the 928 sound like that if you are only changing the exhaust. Flowmaster mufflers have a nice sound and it should work well with your setup.