Originally Posted by IllNastyImpreza
all models of impreza up to the most recent ones(I wana say 06+) are quite unequal legnth...
you would gain some AWESOME sound by switching to a borla header in your car especialy
the 06/07 2.5i is EL factory exhaust manifold (or header if you wish). they might not be excatly EL, but they are tuned somewhat to help the engine make power and it seems to be accepted knowledge that this was one important change that allowed SOA to make the few extra ponies on the 06/07's