Tuning advise needed

Hi Guys,
Got an ss180 with a lml 150 5port engine in it, Had to fit the larger carb as standard carb housing wouldn’t fit without banging into frame so it is fitted with a 24mm klein and a scootrs exhaust.
i am looking to increase performance and speed.
Looking for something that i can bolt on myself that will require no machining or too much tuning experience, can i just buy a cylinder kit or do i need to replace crank and lots of other bits as want to keep this simple, thanks