If you compare the CES headers and TRD Headers, they are both 4-2-1. TRD headers requires you to get the high compression kit in order to max your gain from it. I work at the engineering auto industry.. The engineers (at my work place) told me that the design of the OEM headers are using quite ok, but due to cheap manufacture cost they are not polished (machine made) and have many rough edges on it. That y all the expensive cars most engines are hand built - like ferrari, M3 engines, Corvette ZR6 engines - same concept. Port and polish on stock headers allows you to get the cheapest gain bang for ur buck. The CES headers are ported quite well. Dont forget its only a pienece of steel, so any aussie exhaust ppl that have a good set of hands can port the headers well. Is it worth spending 3 x on TRD, well I dont think so.