i only went for the Japspeed ones because I had them for free
I changed to the Tomei's because they come with extra bungs for my wideband sensors & TBH the quality of the Tomei's is a lot better. Much better made, welds that are a work of art & seemed to be a thicker material (but then they should be for the price)
I can't fault any of the 3 sets I've had though (nor the 1 set of hi flows I've had )