BC/BJ/BF:


BD/BK/BG:
WRX pedals
WRX/STi/Subaru Floormats
08+ Impreza seats in BG
Fixes for Droopy Rearview Mirror


BE/BH:
Dash Removal PDFs
JDM BFM Cluster wiring & retrofit
Center Console Differences

BP/BL:

BM/BR:

BN/BS:

Other miscellaneous:
Factory Accessories that AREN'T prewired
Free Lifetime Seatbelt replacement
Tint Laws in the US
Pictures of other Subaru seats in a Legacy

If you're looking for DIYs, here is a list of interior related DIYs:
INTERIOR DIYs

If you have suggestions for threads to add to it, PM me and I will review them. Thank you.