not on a go tec! leave the hsn flush,lsn 1/2 to 1 full turn in. when engine is broke in I would remove the .015 shim. I have never seen a go-tec with .015shim. Here is what I do with all my go-tecs, I set the idle gap at 1mm,turn the low speed needle in 1/2 turn fire it up and do the idle-little throttle for the first tank. tank 2 I put on ground and start the figure 8's for 4-5 tanks. I have the travel set at 50% for my throttle. That way you won't do anything stupid. After my first 1/2 gallon I then start to watch engine temps,smoke trail. then start to tune appropriately.I do not set my engine to a certain temp. The engine should be around the same temp with every tank you run through it.This gives me an average. Now around the gallon and a half mark I do the shimming. I do the shimming the way mark describes on his web site. Engine to cold,pipe hot=to many shims.engine to hot pipe cold to little shims. I run byrons 30% which I really like. So after doing a few of my engines the way I described above I have a certain starting point. which for me is [after break in] is a total shim pack of .04+the 3 built in= a total of .07. Now just up the way[higher,lower, elevation,outside temps ] I may need to lean a little or fatten up. But this is all done with the lsn. And not much of a change,1/4 turn max either way. Once my hsn is set I leave it alone. The only time I have had to reset the hsn is when I changed the seals on it.