I have a 500 Scrambler 4x4 I just put a new K&N filter in and I picked up a couple of jets stock is a 155.
Now the first jet I tried was a 165 and it ran great the plug was a nice tan color but to me a 155 to a 165 is a big jump just for a filter.

One more thing does anyone have a Supertrap header on there Scrambler and how does it work with it. Is it alot louder ? I am not wanting something real loud but I do enjoy a good thumping sound.

 

Don't forget, it is winter and richer jetting is required due to increased air density. You may have to drop down a size when it gets above 10 C.