dont forget the rb26 box is a lot heavier because it has the transfer case ( for the 4wd ) with it so the rb20 + 25 will be a lot lighter .the 230 kg also includes inlet, exhaust manifolds , turbos , alternator , starter, steering pump but not air cond pump . i havent weighed an sr20 but it should be around 130 for the turbo , dont forget you have 2 cil less and alloy block , the rb 26 block weighs about 60kg.