At the very least you'll need a muffler to use exhaust pressure to help get fuel to the carb. This is because the carbs are too big to give enough suction to draw fuel by themselves. Tuned pipes aren't necessary on a 2 stroke but a properly designed tuned pipe will give a large boost in performance (power) but only over a limited rev range. Older plane engines ran perfectly with an open exhaust but their carbs were much smaller then so had very good suction and didn't need exhaust pressure to the tank.