Nope, and unless you are racing or planning on spending hundreds on parts upgrades, it probably makes more sense to upgrade to a high end bike before upgrading a Joker. The Joker is a fine entry level bike, but basically every single component should be replaced on it if you want to make it lighter and better.
Just going lighter, but not better means you will actually have weaker components that aren't as safe. Then they break, then you come back and whine about how stuff sucks. Well, now you can't whine, because you are being told.
Weight should not be your concern unless you are on a bmx track or unless you are prepared to spend serious money on really good parts and are STILL prepared for them to break or be weaker.
I recommend saving $500.00+ and getting a serious freestyle bike or get one that is really worth putting a lot of upgrades into.