The smaller diameter and longer, straight pipes, the more they rap and the higher the pitch of the exhaust tone.
1-1/2" pipes on a 250 should rap plenty and also help with low end torque.
On my 235 I wouldn't go lower than 1-3/4" pipes, as it would feel choked at higher rpm and freeway driving.
For city only and midrange rpm - perfect.
I have 2" pipes on mine and that feels still choked on the freeway above 2500 rpm.
For the 250 the numbers are probably about the same, I would think.
