TTO,
To save weight. The TRDS covers, the xmsn-driven Stby Generator, most if not all of the pax seats and the P2 seat (if not reqd) went the same way. Occasionally the pax doors would go too. We toyed with taking off the engine cowlings but they had firewires on them so we drew the line at that.
All so it could get off the ground with me in it!
Some of the locations we flew into were 'hairy' to say the least and we wanted to be as light as possible.