I just got a FMF powercore and a K&N wondering what jets to use the recommend 150/155 My elavation is around 1000 ft I'm a little new to this tuning factor so any advice would be great thanks Ry

 

I am new also, but if it were me, I would start off on the rich side. Then you can go down. I believe I read this on CT'S website, or in dirtwheels(not sure).

 

Your 150/155 sounds like a good starting point...one full step fatter may be about right or possible a little lean at your elev. which is basically sea level fir jetting purposes.
Of course, as I preach to all who'll listen, the only real way to know is to do a test ride on a brand new plug and read the plug to see what it tells you.