Building new custom exhaust

[VR4Play]

I have an 02 Suburban with 5.3 FF that I use for towing my karting trailer around. I'm looking to find a little more power out of it and have started with doing a Volant intake and am currently working on the exhaust. I've started with a Flo-Pro 2504 muffler that is dual 3" in and dual 2.5" out. It is supposed to flow much better than the stock muffler and is only slightly louder than stock which is what I was looking for. I am looking at doing the headers next and have been looking at the Speed Engineering long tubes in 1 3/4". My question is about the tubing from the headers to the muffler. I shouldn't need 3" being N/A and only 5.3 so was thinking of reducing it down to 2.5" as to try and not lose down low torque. I am going to be adding an x-pipe as close as possible to the headers. What are most other people doing? My next mod after this will be BTR truck norris cam. Thanks

 

[Noggles]

I had headers and 3" exhaust on my old 5.3 Silverado and I didn't notice any lack of low-end torque. I also went with TSP headers over SE (I HATE the SE headers on my trans am) and a pacesetter off road y pipe (the TSP was out of stock at the time) to a single in and single out Borla xr1 muffler. IMO true duals aren't worth doing if the vehicle didn't come with them from the factory unless you just have to have the x pipe sound. For my catback section of the exhaust I went with piping from Dynomax and then just made sure the muffler I chose was the same length as the walker catback muffler was and everything fit together great.