If you are referring to the YX150 in the Atomik, the 10cc difference is the least of your worries... They run a CRF style head as opposed to the KLX head that YX also produce
i got a pitpro 155z (zongshen) now so i think i have the klx style head...
there better because of the higher ports imo whereas the honda style makes a pretty sharp bend i dunno i have not had the head off yet lol
i think the close range gearbox will make all the difference