They are HM341's, they are the third incarnation of the Honda 4 into 4, i think the first ones were not numbered then the HM300's then the HM341's, i think they are for K3 and higher models, the HM 300's were a better breathing {less restricted} pipe. If i were putting pipes on a K1 i would go for 300's but these will definitely fit the K1..
Mick