I typed an exceedingly longer response, but then deleted it all because I'm grumpy. I'm reminded of a quote.



"If folks are left behind [to the fringe of society], bright minds mutate and stagnate. These folks are potential scientists gone wrong and their natural inquisitiveness and rejection to the norm could be a benefit to science if they were more scientifically literate."

In any event, despite the wealth of knowledge accrued from multiple failures concluding in a greatly similar solution, the goal here is fixed and counter to what we generally seek. After re-reading the original post, it's clear that being QUIET [not to be confused with merely tolerable] is of more importance than performance, and that's the OP's prerogative. I'd be interested if the OP should just carry on with the experiment as it's justification is preordained and report back if he truly achieved a whisper quiet, albeit castrated, turbo Miata.

 

^ what he said.

Also, I realize you're looking for more concrete information, like "you will spool 200 rpm sooner with a 2.5" Magnaflow compared to a 2.5" thrush turbo muffler." However, that information is of very little use to the general forum membership because most (all?) Of us who have used the recommended suitcase Magnaflow have been satisfied with the results.

 

I would summarize the priorities thusly:
1) be almost free.
2) be a very specific type of quiet
3) make a poorly performing turbo setup perform minimally more poorly.

Stated that way, I can see why we’re all having a hard time relating.

 

You will not experience deep tone with that tiny obstructive muffler after a turbo. When you really try to put some volume through it, it will sound like a Crown Victoria or an Electrolux vacuum cleaner, take your pick.

From my decades of personal experience I can tell you many of those mufflers are smaller diameter tubing inside than outside. They commonly are expanded from a smaller size at the tips for mounting. What you see and the cute little representative picture is not always what you get. And with the little tiny case length you have very few perforations in the pipe for the gases to pass through. With that type of muffler you want a very long case for any appreciable flow and you want to hope like hell they actually perforate most of the pipe and not just a few inches of it. Again, it is so the manufacturer really doesn't care about your performance. Neither do the Guatemalans who built it.

 

I literally laughed out loud at 11.5psi @ 4400rpm. OP, that is atrocious.

Literally anything you do will be better than your current setup. If you insist on sticking with that shitty $25 muffler, it will still be better than what you have now. The Magnaflow that literally everyone on this forum uses is better still, and will also still be quiet enough for you.

If you actually cared about spool, you would dump that 2871R clone and get a geniune used Nissan turbo.

 

Wanna race from a rolllllllll bro?

 

I do I do I do! Pick me pick me!