You can always go back.
A new arrester assy is $90, more than I would pay. But there are a lot of people who may still have the ones that they removed. You should be able to find one for under $30, mine wound up in Thailand!
A proper power-up mod requires you to remove the snorkel and the baffle and the power-up kit from Honda. You will get a substantial power gain. The downside is the bike will be equally louder. Not as bad as a 2 stroke but definitely enough your neighbors will know when you are ridding. Pro Circuit makes a pipe that will do the job but I have no experience with it.
If you want power and low noise then you are going to spend some money.
I ride along a creek that borders four subdivisions. All I do is go easy when I am close. Once I hit the trees its balls-out. I have no troubles with the neighbors.