[Rally]

I'm probably not the one to ask about exhaust work, as I haven't changed my stock out yet. However, I DO know some answers to your questions.

As far as loudness goes, 2 chamber Flows will be louder than 3 chamber Flows, since the 3 chambers are more restrictive than the 2. That is also why you can make marginally more power with the 2. However, swapping the catback doesn't improve power anywhere near changing the catpipe would, since the catalytic converters are the real bottleneck in the exhaust setup... A catback swap may be good for 5 rwhp or so, while a catpipe will add approximately 15-20 rwhp. Both of these scenarios are in a mildly modded car.

Most people have the 2 chamber Flows, and love the sound. Personally, I am looking at the Magnaflow catback. This is a flow-through muffler design that will go well with the catted x-pipe that I am planning on getting. Generally, with a catted x-pipe, a flow-through muffler design seems to work well. With a catted h-pipe, the chambered mufflers work well. This has to do with the flow characteristics of the different catpipes. I also like the Magnaflow because it has a milder sound at idle, and low rpms (great since a loud exhaust would be a bit much with a convertible) and gets pretty wicked at higher rpms.

Bassani exhaust products are generally considered top-notch, although there continues to be some debate about the quality of the cats used in their catpipes. Many people have reported failures there.

Hope this was of some help for you. If you do a little poking around here in the archives, yo should find a plethora of information about all of these topics. Like I said, I am no expert, and am learning myself.