I would just wait until your warrently is over. The best thing to do is replace parts as they go. For example, when the stock brakes went, I upgraded them like I wanted to. Same will go for the suspension, etc, etc. In terms of performance mods, I didn't feel like doing any to this car, but in the past I usually do them when the warrenty has expired to play it safe. I don't think there is a huge difference between the 177hp and 190hp engines in terms of performance, therefore I would say it is not worth to try and gain more power at this point. Like someone else said, I would get new rims and tires.

Congrats on your new ride, my friend just got the LX auto sedan and he loves it. It is even bigger than mine! A guy I work with got an EX sedan in stick, don't know how he found one, but he did. They are great cars and will last a long time, especially if you stay up on the maintenance.