Exhaust System on 77 Suburban C-10/2WD with 454

I am in the market for new mufflers on my 77 Suburban C-10/2WD with a low ratio axle that has a 454. It presently has 2.5 inch head pipes, 2.0 inch mufflers and 2.0 inch tailpipes. I would like to go 2.5 inch all the way with Flowmaster 50 Delta Flows as they would have a nice strong note but wouldn't rattle the neighbors windows. I live in the desert of Arizona and plan on keeps my burban for many years. I've been to three muffler shops and got the following stories:

1. Speed Shop - yes you need to go with 2.5 inch all the way, anything less reduces you power and fuel economy. Says Flowmaster 50 Delta Flows are good mufflers. Wants to cut at the beginning of the long straight pipe and replace all the way back with aluminized 2.5 inch pipe and 2.5" in / 2.5" out Flowmaster 50 DF. Price 0

1. Fletchers Automotive - doesn't think the long straight pipes need to be replaced. Says the flowmasters are good mufflers, would go with 2.5" in /

2.25" out mufflers and aluminized 2.25 inch tailpipes. $400

1. Midas - wants to go with Ravin mufflers (Midas brand?? Only been out for

3 years) Says Flowmasters baffles fall apart inside and rattle. Aluminized pipe is a waste. Thinks existing 2.0 inch tailpipes are sufficient even if I upgrade the performance of the engine some. Doesn't think that 2.5 inch pipes will even fit in vehicle! Says long pipes will last 5 years so no need to replace. In other words he just wants to cut out my existing muffler and weld in a 2.25 inch Ravin 55 Performance muffler. $230

Now my questions are:

1. Is it best to go with 2.5 inch pipe all the way? I might do some minor to mediocre engine performance upgrades in the future.

1. Any opinions on Ravin Performance 55 mufflers or Flowmaster 50 Delta flows. Any problems seen with either of these mufflers? Both are supposed to be lifetime warranties.

Thanks, Bob