Exhaust size question

The single tailpipe behind the muffler is 2 3/4". The tubing in front of the muffler is all over the map, from as small as 2 1/8" to 2 3/8" depending on where you measure it.

Go with 2 1/4", you shouldn't lose any low end. Back when I had 2 1/2" true duals, I lost my low end, but I got it back by adding "Helmholtz Resonators" (Thanks to Mr. C's input and Keiths install). BTW I tried both the H and X pipe and I did Not notice a difference. Post back after you do this mod. I want to know your true feedback..

using 2 1/4" seemed to be too restrictive, it made a horrible blowing sound and would blow exhaust on you from 10' away......at idle. 2.5" seemed to work better but it lost a lot of low end.

you'd want to tie back into your stock tailpipe to keep from losing low end. search BAmufflers on this site for more info. Also google search 'how a properly built exhaust system works'

I thought using 2 1/4" would be too small as well. I had many vehicles that I put true duals with no cat or crossover, Flow's using 2 1/2" and woke 'em right up, huge difference. I find it weird that a motor like these works best with small diameter pipe. I'm mainly looking for the sound, but any performance gain would be nice.

FWIW my n/a 5.7 had its best ET with a 2.5" cat back system but the low end torque was softened a bit. With the close ratios of the six speed the reduced torque may not be as much of an issue at the drag strip because it can keep the revs up most of the time. It did feel a little soft at light throttle / just commuting though. Later on when my cats rot off (cough-cough) I intend to get longtubes and use 2.5" tubing until after the muffler, then neck down in a smooth taper back into the 2.25" tailpipes. Hopefully the exhaust has cooled enough back there that the smaller tubes are not an issue.

Don't do much drag racing with the truck, in fact I've never had it to the floor. Really don't need to mash it, it gets up n goes pretty good. I take my car out to have fun with (79 Malibu with a 454 and 4-speed, 3.42 posi, THAT is fun!!!!)

As I said before I don't want to loose any torque. Maybe in a couple years when my cats rust off, I will put something different on, maybe change it up and see what works and what don't. Buddy does nice exhaust work, basically only have to pay the pipe. I wouldn't mind getting some long tubes, that would wake it up....

Did I say that out loud?? Must be the wife yelling at me got me confused....