Hi nadweji, sounds like great upgrades have been done

Swaybar makes a difference only when cornering

Yes, manual transmission will make huge difference in acceleration and increased fuel economy. 4-speed works very well. 5-speed is better for fuel economy, but 4-speed is faster acceleration. Both have the same top speed (90 mph). I drove my 1200 with 4-speed all the way to San Diego and back to Seattle