Run light high pressure tires in the back with a XC ultralight tube, Swap out your crank for a lighter BMX crank. You would have to look up whats available for your BB type . I run a deity now But I am switching to a fly bikes crank @ 841g's that arms and spindle 187g's add for the BB. a KMC superlight chain. Get lighter pedals. Like PC or metal if you can afford a set of 400g joints. Replace the seat with lighter one and either get a shim to run a BMX 25.4 stolen thermalight post ( made of PC) or just run a combo seat. would come out to like 300g's for that set up. all in all stock parts are super heavy .