If you want the knock sensor, use a USDM P30, it's a P28 with a knock sensor, and it came on USDM B16 sols like mine. They are rare and $$$ though. I would just use a P28 and get it chipped. I can take care of the chipping for you if you need, I'm a professional electronics technician..
I can furnish references if you want, I've chipped a lot of ECUs..