Perhaps they are not same. SIR civic kind like more stronger than the VTI so I assume its not the same. Well, the SIR sounds cooler and probably got driven harder so the spring are diff. I would suggest the VTI, it has less HP (mayberry style) so it wasn't mistaken as a racing car like the SIR might have.
VTi has a smaller engine which is a Single Overhead Camshaft (SOHC) while SiR has a Double-Overhead Camshaft (DOHC). SiR's engine is much much heavier than of the VTi's SOHC. I think their coil spring has a difference with its thickness. Not sure really if they do have different springs since I kept my stock coil springs with me when I lowered my VTi so I didn't have that same kind of problem when I returned it to its original state and didn't bother to research about it... I'm just giving you an idea that it should be different. If ever you don't find your answer anywhere try and call Honda of any branch and talk to their parts and services dept.