RB series had so much more aftermarket support, where as my 1J has bugger all.
Just recently did my dumps cost me $550 (+ postage) to get it custom made, where as most RB25 dumps are less then $400 for a decent one.
1Js run coil packs and spit fire dont even make them, and toyota wants over $800 for the set.
But gota love 1Js for the ability to handle over 20psi of boost on stock internal day in day out. As some of the guys on soarer central are doing to get over 250-300+rwkw.