why dont you just get a TRD
/kazuma exhaust? if you want loud and high flow,thats the way to go. No cat, no resonator.. loud as hell. and if your wondering if the CEL will go on because of no cat, it wont because the kazuma has a place where you put the O2 sensor.
2000 GT-S - SOLD, 12/2003
1986 AE86 GT-S - STOLEN, unrecovered, 2/2004
1985 AE86 GT-S - built 4AGTE, SOLD 10/2009
2004 Camry LE, SOLD, 5/2007-10/2007
1994 GS300, 2JZGTE, HKS T04Z, 10/07-Current