There are many things you can do to improve any model from any year of the Brompton bike. I should know as I have done so successfully with my own Brompton C3 by adding a new saddle (minus the Saddle Adapter Pin with Quick Release-I did not need it), rotating the brake levers upward very slightly to reach my fingers for improve comfort and braking leverage. and even decent Kool Stop Brake pads. All of my upgrades were far less than I expect to pay at less than 100 US dollars. I recommend that you visit your own Brompton dealer as well as other bike retail sources to see what is offered to you. Personally I think that the part: Saddle Adapter Pin with Quick Release is what you need. Over here in the US, C.M.Wasson Co. offers the part. I like the ability to fine tune your height as well as pedaling position with ease as seen with his own photos. You also gain the ability to remove the saddle without tools when you store the bike or travel with it.

Visit his link for more information on this and other parts and accessories: http://www.foldabikes.com/PriceListHTML/npricelist.php