Originally Posted by DiscoGsus
The muffler doesn't affect anything except the noise.
A protune adds little to the package for other people.
The intake, DP, and FMIC greatly affected the tune you received, so only a 2006 STi with the EXACT same mods gain something from having that map.
a stock 2.5 muffler compared to a 3" straight pipe will effect flow.
Of course only a 2006 Sti can rock this because its for a 2006 only.
Turbo XS DP, Perrin FMIC and standard SPT Intake are very common, Common, Common, Common mods. and very basic.