any chambered muffler won't be a straight through design... if you really want that... magnaflow is the way to go, and they sound comparable to flowmaster. as for me, I got a mustang-tuned turbo muffler, single chamber. the catback w/ those was from Jegs (well, I got them somewhere else, but same thing) pretty much, for the name, flowmaster is trademarked, so no other company can claim them if they're not... but there are very comparable designs out there... www.jegs.com has the catback for our cars for like $170 I think, w/ free shipping, and it comes w/ the 2 flowtubes, the mufflers, and the catback piping... all 2.5"
personally, in my experience... the cheap or no-name brand equipment work just as well, if not better than the large name brand stuff... all the pipe are is metal in a tube format... the mufflers are pretty much the same too... sound-deadening material, and some holes in a tube going through it...
well, in my surcumstances... I need to be quiet at idle... which is exactly what I have... when a cop pulls up next to me at a light, and his windows are down (or even if theyre up!) I dont' want him to say, oh, illegal exhaust, let's pull him over and ticket everything!... not to mention, it's a pretty cool sleeper exhaust