When it comes to a street car, many things are more trouble than they're worth. You build a 550 hp motor but the mufflers you use kill 25 hp. Will you really ever notice that ?!?! And was your combo optimal to begin with, with parts that are designed to work together or did you opt for something like a tunnel ram just because you liked the looks.

Truthfully, building the optimum system such as Mr Vizards's would be a real pain in the ass and expensive. Assuming everything is carefully chosen right down to the headers, you now have to optimize the collector tubes to the custom expansion box(es). Then find mufflers that flow the necessary CFM. Then there's the issue of fitting all this under the car. Well congratulations. Now someone with a bigger cam comes along and kicks your ass.

Its nice to see all this research but applying its is quite another matter.