Up and coming mods LTs, Y Pipe, CAI, & Tune

In the next few months I plan to install Pacesetter LTs and Y pipes, Volant CAI, and get a Nelson tune. What kind of horse power gains would be expected from these mods.

Also I have a GM peformance cat back dual exhaust (PN 17802149) it is a bolt on kit and I would like to just replace the muffler does anyone know the deminsion of that particular muffler. I am in the middle of the Gulf of Mexico working and would like to order a replacement so it is at home before I get there.