The EK 4 is actually equipped with the b16a DOHC VTEC engine system, while the EK 9 on the contrast comes with the b16b DOHC VTEC engine system. The EK 4 usually comes with just four nuts, while the EK 9 usually comes with five nuts. When comparing the socks and springs of EK 4 and EK 9, the EK 9 actually comes with shocks and springs that are better than the EK 4.
While EK 9 comes with 22 mm rear ARB, EK 4 comes with a 13 mm rear ARB. The EK 9 possesses a seam-welded chassis and stiff bars behind the bumpers, which are all absent in EK 4. In terms of steering, EK 4 has a better feeling of power steering than EK 9. The EK 4 seems to gives a heavy feeling, and it may also roll badly on corners in comparison to the EK 9.