I have got an almost identical setup on my bike, and i am running 33's. It still has plenty of low end power. I can run it around the local MX track, or through the woods and keep up with most people.
Im running shearer's, and thats not really helping my bottom, the pipes you have on there should help a bit more as well.
Go with the 33's decent low end, great mid / top, easy to tune, and idle as good if not better than the stockers