i got a trailblazer 400 should i put a k&n filter in first then reed or the the other way around because i have money for a k&n now?

 

You will NOTICE more gains with a filter.

 

tb400,the k&n is the first thing to get when you first buy your 400 2 stroke,take some rides as you want with it then,you can make test plug to see if jets are fine to get more performance out of it then with proper jetting,keep the clutchs clean.
reed should be your next step.