I've got the 40 series on my ST using the stock pipe and it's not loud at all, it has a nice deep tone at low revs bt you really can't notice it when you get above 2500 rpm.
My stock Michelins did this also and I ran 30 in the front and 35 in the rear as advised in the door. I still got 62k miles out of them but the inner and outer edges were slick with some tread remaining in the middle.