what are the +/- of going with a true dual exhaust vs a one muffler dual outlet cat back?

currently i am in negotiations for a new red fx4 supercab. we will see what tomorrow will bring, hopefully a new truck. then i will have to decide what type exhuast will be best for my truck.
i have heard that the true dual pipes can cause a loss of back pressure resulting in lower torque down low, but will help horsepower at top end. is this fact or speculation? does it make any statiscal difference in staying with the one muffler or going to two of them?

thanks for any and all comments concerning the exhaust questions. in the future i do see long tubes along with the cat back pipes/mufflers.

 

True duals if done right will not cause a loss in back pressure. I've had them on my old S-10 with a anemic at best 2.8L V6. I actually gained performance all around. You need to have a x pipe after the cats, or you could delete them all together if you don't have emmissions testing in your area. Keep the piping around 2.25" if you aren't going to mod it too much. Step up to 2.5" if you are gonna do more than a intake, headers, chip/tuner. The true duals also provide the best sound IMO. I've got Dynomax Bullets on my V8 S-10 and its deffinately loud. Sounded like I'm back at the dragstrip everytime I fired it up Hope this helps...if you need anything else, you can reach me on AIM as Chaosrealm1

 

thanks for the info. my local muffler shop told me that the f150 generally lose a little low end torque with the dual ex. something to do with the new cams and ford tune. the guy that told me this use to work with a national sprint car team so he knows his stuff.
the sad news, is that i sold my mustang but did not get the new truck. gonna pay off cc debt work on buying a house and then get a new 150 in a year or two. but when i do i want to go full exhaust with the true dually's.

 

You're welcome. I think you would LOVE those Dynomax Bullets if your into a true bada$$ sound. Flowmasters have just gotten old, and Spintech is WAY too overpriced. Maybe if you used the Hypertech tuner? Or swapped to a better set of cams from SHM at the same time you wouldn't get the loss of low end. I know with my V8, I could smoke them at will with 295/50s that stuck like glue. I never could tell of any lowend loss, but I've never played with Sohc or Dohc motors...Soon to change as I'm planning on a new purchase in about a year. 2005 F-150 if I can get a 5spd..