I am running 336im's in all 4 doors. I have the gain down a bit on the rears, it is just for fill, but i like a lot of 'body' with my music. I plan to upgrade to 346is's up front some day to improve the soundstage. Each door currently gets 50W from a Nakamichi PA504. It's plenty loud enough.
I would go for # 3 - Your amp is awesome on SQ, and the power is more than adequte. Run 75W to each door and be done with it. Later you can upgrade your rears, or better yet, figur out houw to stuff some 308rs.2's in each rear door.
Mark
