Simple question are the Prothane rear trailing arm bushings legal in STS I would think they are. Car being 89-91 Civic Si.

 

Many of the (2004 season) ST rules and guidelines can be found here: http://www.moutons.org/sccasol...NSION

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">14.8.B Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location. Offset bushings may be used. In a replacement bushing the amount of metal relative to the amount of non-metallic material may not be increased. This does not authorize a change in type of bushing (for example ball and socket replacing a cylindrical bushing), or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the Stock bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accomodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings, but may serve no other purpose than that of retaining the bushing in the desired position.</TD></TR></TABLE>
So yes, you can use poly bushings in STS.

I would actually recommend going with OEM Honda or Mugen rubber bushings for the rear trailing arm, though. The big solid polyurethane bushings apparently don't allow enough of the multi-axis movement required of that particular bushing, which in turn can cause the suspension to bind. You can find more information on that issue in the RR/AX forum.