I have seen some people on here have made their own mufflers and I had some questions about the theory that goes into them.

With straight through mufflers (perforated tube glasspack design) how does the size of the perforations affect sound and flow properties. should the perf tube allow as much air to pass as possible without packing comming through or is there a such thing as too much flow area?

if there is not room for a long case does increasing the width help control the sound. does overall volume of packing determine sound attenuation or is shape a large factor?

Should the internal pipe be smaller than the inlet outlet of the muffler to control sound or would this be unecessary restriction?

can plain steel be used for inside perforated sheet? Would steel with high temp paint be sufficient on the inside?

how tight should fiberglass packing be? loose like it is when you put it in say the wall of a house or packed tight?

Thanks for any info. I am about to embark on a SBC Fiero conversion and exhaust space is limited. I am a sheet metal fabricator so the tools and materials are not a problem but I have never designed a muffler so any help would be great.