Don't know about BA/BF but in FG, the rear seats are very easy to remove. The base weighs nothing but the 2 split back rests are surprisingly heavy.
Quick disconnection of negative battery terminal to stop an airbag blowing up in your face, and the front passenger seat is a quick removel job too with an electric drill and torx socket adapter.
Dry cell or lithium battery if you have the $.
Some light cast rims like RPF01's or any forged alloys save a heap of unsprung weight. 2 piece front brake rotors.
Lots of Fibreglass bonnets around now on the market to choose from.
With a sorted anti-surge fuel supply set up, low tank levels can be used safely at the track.
Lay off the junk food and beer for a fortnight....but let's not get that serious hey.....
All this adds up to a substantial and noticeable weight saving. Not each component by itself, but the whole weight saving package does.
It's all about getting personal pb's, even if it is a tenth or 2, it's still a pb.
If you are at your own personal limit for times, I'm all for a good diet.