im probably gonna go with the 29s(kind of scared a 28 will be too tight). how much do these shrink all around, and stretch in the waist?

I'm 5'6 about 125lbs. I'm a 27 in my warehouse 660s, but I'm looking for something much slimmer. Should I get a 28 in the 666s? (I'm about a 29.5 waist)