I wanted to bring this thread back and get some more replies. I had planned on replacing my existing exhaust system this past year but other things came up. So, I am going to try and replace it this coming Winter.

I already have the TTi SB headers + 2.5" reducers. I am currently running tru-duals back to the original 6.2" diameter mufflers (18" case length, 2.25" pipe) and then thru the stock 2" R/T tips.
My plan is to remove the existing pipe, mufflers, and tips and buy the TTi 2.5" X-pipe assembly but with the Muffler Delete pipes (under the seats) that they sell. I want to add my own flavor of mufflers to the system and try to keep as wide open of an exhaust that I can. I will then buy the aftermarket SS R/T 2.5" exhaust tips.

After discussing this in detail with Magnaflow, my goal is to have a DEEP sounding exhaust at idle and at a cruise. I also want to use their 530cfm free flowing series of mufflers (Not the XL series which is a very restrictive 3 chamber design).
Note: My existing 6.25" x 18" case OE style mufflers are about 175cfm each.
I also want to keep the sound down so that I don't piss off the neighbors or the police and I want to only use rear mounted mufflers.
After searching through several muffler brands, sizes and shapes, and after many emails with the Magnaflow tech, I decided on a set of round MF mufflers that will mount in the "area" of the OE mufflers. I had a few choices of mufflers and I gave these to the tech to try and get some idea about the loudness of these mufflers. I first considered the front mounted mufflers, then I considered mounting both front and rear, and now I am leaning towards the rear mounted mufflers only. This is the reference that he gave me for noise:


""On a scale of 1 (stock) - 10 (straight pipes) I would rank the mufflers as follows (530cfm):

A) front mufflers only - 5/6 (#11226 = 4" x 9" x 14")
B) Rear mufflers only - 8 (#12866 = 5" dia. x 14")
C) Both front/rear mufflers - 2/3
D) Rear mufflers 6" dia. x 14" - 5/6 (#12616)
E) rear mufflers 6" dia. x 18" - 4/5 (#12646)
You may get a fair amount of drone with just the rear small round mufflers.""


My existing 6.25" OE mufflers are at least 13 years old and they are worn out, but no drone from idle to WOT. They are pretty darn loud at WOT. I consider them to be quiet at idle and at cruise and I think that they are too quiet. So from the above reference, I am aiming for the middle of the road for loudness and I am leaning towards the rear mounted 6" diameter x 14" long mufflers mounted beside the tank.
Once I get the TTI X-pipe, muffler delete pipes, and R/T tips installed, I will know exactly how much room I have to mount these mufflers. The OE muffler exits are offset towards the bottom, and the MF are straight through. All this means is that the MF muffler will hang down lower at the exhaust tip. But since this muffler is 6" shorter than the OE, I plan on moving the MG muffler towards the front of the car a few inches so that the muffler "may" not be seen when looking at the rear of the car. Plus if this 14" muffler is too loud, I can go for the 6" x 18" muffler and still have some room.
I am hoping that the combination of the 2.5" pipe, X-pipe, and the full length exhaust will keep the overall loudness down enough so that I don't have to buy the 18" mufflers or worse case, buy a set of oval mufflers to mount under the seats. I won't have all of my parts until mid-Winter, so I still have some time to think it through.

If anyone new has mounted their 2.5" mufflers beside the tank on their B or E bodies this past season, please feel free to give your opinions.
Thanks again to Davenc for all of the db references on his 3" system!



Thanks to all.