JDM product quality control usually exceeds the rest of the world (some would argue it also exceeds their own export version of the same product) because JDM has an extremely low tolerance with imperfections, even in today's broke ass Japan.
But I don't know why you guys are comparing aftermarket competition exhausts with factory optional sports exhausts even if the manufacturer is indeed the same. Factory optional sports exhausts regardless of car brand rarely would have a rasp sound even at full throttle.
Not everybody wants a racing exhaust, at least I don't.
"XaCAR 86＆BRZ Vol.2（12月10日発売号）のマフラー特集の動画です。Part１では、FUJITSUBO／STI ／HKS／R MAGIC／BARUTA／ZELE／REMUSのサウンドをお届けします。"
[ame="https://www.youtube.com/watch?v=QV_ndoTr08E"]XaCAR 86＆BRZ Vol.2　マフラー特集Part1 - YouTube[/ame]
EDIT: I found out that Fujitsubo made the exhaust for their new WRX STI Nurburgring 24 hour race car (per Fujitsubo 2015 PV on YouTube).
However after searching on Google, throughout the years STI Sport Mufflers were actually made by Sakamoto Industry (it was actually stamped on it along with Subaru logo, same polished finish). Sakamoto is exhaust OEM for Fuji Heavy Industries.
The 2009 WRX STI Nurburgring 24 hour race car also had a Sakamoto exhaust. I'm not sure when Fujitsubo became a sponsor (if this even means anything), the BRZ STI muffler is a 2012 product.
The current BRZ STI Sports Muffler only has a JARI certification number and the muffler model MMAS1 stamped (they are always stamped "MMxxx" even with the old ones). For comparison, I also notice modern Subaru stock brakes are no longer stamped Tokico, but just Subaru.
Confirmed from STI Japan that it's not a Sakamoto.