If it's performance you're after go for the sports system minus the cannon. If you're with a stock/mild 4k 1.75" is the biggest you should go. 2" is a little too much. I have a 2" sports system in my KE70 with a 5K. It sounds cool, but at the end of the day I wish I had gone with a 1.75" just because mine is a little on the loud side. Long highway driving is a bit of a bad experience. You'll realise that unless you're doing this to a track car, practicality is greater than trying to get maximum cool factor or those few extra horses. By all means a sports exhaust is a great idea (way better than a cannon)m but not to race car spec for a daily.
To go on a little further, I just bought a subaru wagon (the older ones), which has a sports exhaust on it. It's hardly noticeable at idle, subtle at regular and highway driving and it only really gets louder when you plant it. It's brilliant! Everyone still comments on how it sounds nice, but it's never too loud. Being a young person there are times I wish my KE70 were a little quieter.