so i have a 2004 sti and i was looking into exauhsts.... and my buddy has a RSR exmag that he had for his sti but never used cuz he totalled his car.... soooooo he offered it to me cheap... how good is this system? and performance wise how does teh RSR downpipe sound and what kind of preformance will i get out of this combo? also... i have a 05' wrx i had a borla exahust w/ invidia downpipe on there.... would it b better to swap that on to my STI or take the RSR from my buddy and get a RSR dp?