Sapphys can be made to go round corners, the issue with them is that each end doesn't know what the other end is doing, this is caused by the dreadful rear end, and in particular the diff hanger bush, swapping this one bit to a poly absolutely transforms the car, although it will still be harder to get the best out of, due to the superior chassis of the beemer imo.
Someone around my way had a R reg m3 evo, and there was nothing in it between my stage1(and a bit) 280bhp cos and his m3 evo, nop doubt due to bis 316bhp but 200KG extra weight, at the higher speeds I just started pulling away, but really only just.
tabetha