Rebuilding your engine with forged pistons doesn't really make sense. The only real benefit you'll see from lighter stronger pistons is if you are revving above the stock red line and/or pushing more power and if your doing either of these you should be replacing the rods before anything else as they are the weakest link. In my opinion using higher performance pistons while operating in the original engine specifications and environment will yield a very minimal advantage and is not worth the added cost, especially considering the durability and longevity of the OEM cast pistons. My old Sidekick had 320000KM and my current has 230000KM and there pistons are/were in great shape and many others are at much higher mileage . Also while the crankshaft is balanced on it's own and changing the pistons (assuming there all the same weight) should keep it balanced, but it's not to say the lighter pistons wont change the engines harmonic characteristics.
Suzuki Swift Racing Parts - Performance Parts by Suzuki Racing Development - Suzuki Swift Racing Parts - Performance Parts by Suzuki Racing Development
