I had a custom true dual 2.5" on my 93 Tbird LX 5.0, that was originally on my 3.8 car.
When I installed it on my 3.8 LX back in 2001, I used high flow cats, dual Magnaflows (looked almost identical to the Borlas they had), deleted the resonator, and used big giant fart can tips. The car sounded like a raspy fart. Later on I added a crossover pipe, and turn down exhaust tips, and the difference was immediately noticed before I even left the exhaust shop. More punchy on the low end, and it sounded actually pretty good - I was impressed, and the guys at the shop were as well. Another couple years farther down the line, I got a 93 LX 5.0 and of course had to move the exhaust over to that car. It made a very noticeable power increase on the V8 car, and it sounded absolutely wicked! On a cold day, it was extra loud and deep once the motor and exhaust started warming up. It did have a lot of drone between 65-75 mph mostly, constantly pissed my girlfriend off, and it would have been a LOT worse if I got the flowmasters.
I'm going to do the exhaust on my Mark before the end of the year hopefully. I am looking to replicate the setup I mentioned above as closely as possible; I can only imagine how nice it will sound with this free revving 32 valve beast! I cant help but to wonder if it will actually be louder than my 302 was with the same exhaust.
Also important to point out... The Magnaflows are built VERY well and give the best bang for the buck, and the flowmasters I saw at the shop looked like they were built like crap (not stainless steel). I was told within 6-7 years, the chambered mufflers usually need to be changed out because they are prone to rot, even over here in Los Angeles. In fact, I had noticed that all the Magnaflows I looked at were stainless steel, and had a straight throw flow design, and reminded me of the overpriced, and overrated Borla mufflers.