Hey guys i have recently bought a 2004 350gt, i was looking at getting a custom exhaust system made, i was thinking about having 2 seperate 2,5" exhausts with a high flow cat and a high flow muffler on each one coming from the extractors, will i loose power because of too little back pressure, will i have to get a new ecu/tune. Has anyone tried this? Your help would be grately appreciated.