Thanks Tai, i sort of lucked out so far...
the 4 channel zapco couldn't even fit in the spare tire compartment let alone the the side walls (yes, just like everyone said).
what
6spdcoupe ended up doing was mounting the amp to the underside of the rear parcel shelf inside the trunk 'ceiling'. Brilliant! Its out of sight, i get to lay my seats down for cargo, and the spare compartment stays open...
im pretty stoked to pick the car up, maybe late tonight or hopefully tomorrow. still needs to finish the install, scope, and adjust the amp...
fitting in the rainbow SLCs took some modding to the speaker housing itself in order to get them to 'drop in' on the E92 door panel (fwiw, on the E90 its not an issue).