i used offset inlet and center outlet on both of my stangs.:mmm: i would go with a set of delta 40's.those are two chambers . the delta flows don't have the drone going down the interstate. now the regular two chambers do .i know, i have a set of each .i just love how they sound on a small block ford.
Only as a suggestion I would recomend a good read out of Mustang & Fords, October 2000 issue before setting course for flowmasters. Of course this depends on whether there are headers (type) or hi-po exhaust manifolds, crossovers or "x"pipe or straight run, size of pipe, dumps or out to the vallence, etc.
I have decided to keep the headers I have (I got them used 10 years ago and have no idea who makes them, but hey $20 is a good deal!). They are long tube headers, then I am going to 2.5 inch all the way back, H pipe just behind the headers and dual flowmasters forward of the rear axle (like the 66 style duals). It seemed that artical sparked more controversy than it solved. I don't think there is anything inheretly wrong with this setup and the only way I will be able to prove that x pipe vs h pipe, step down in size after the mufflers vs same size, flowmaster vs dynomax, etc etc, is to spend a bunch of money on dyno time. Unless is sounds like ass and runs like a dog I will be satisfied with it!
i think you will be happy with the flowmasters ,i know that i am . they sound bad ass on both of my stangs. when you pull up next to someone at a stoplight and they say that it sounds bad ass , you will be very happy . i hear that all the time . even if they don't say it you know they are thinking it .you will notice a difference in power also . i went with 2 1/2" pipe allthe way back from the headers.
I have long tube headers and Dynomax mufflers. It sounds awesome (if I do say so myself), and best of all they're easy on the ears during normal cruising. Price was good too. As for comparisons, what's a few HP either way when sound matters so much?!