I totally agree with this, but I found a WRX 5zigen exhaust local that I can afford. The seller says it should be 2.75in piping, still too big but, not as too big as those 3in Ebay $130 exhausts. lolI would say stick with 2.5" as the max for an N/A build. After that your just adding unnecessary weight to an already slow car
I did search, didnt find the answer I was looking for and so I asked. Also, I have an OBS, not an RS. I have a 130hp-ish econobox and would like to preserve as much as that power as I can since I have no plans of swapping this car. Finally, I have no complex about myself and you no reason to be a dick, sir.Holy i-don't-know-how-to-search batman! You're worried about power loss in a 168hp n/a econobox? Get over yourself...
3", 2.5", 12" do what you want.
No engine on the planet needs or wants or benefits from backpressure - backpressure is a restriction, not an attribute. The idea behind proper scavaging is the reduce backpressure, and increase pumping velocity and volume