Have you treid to beat a 450 on it
You should beat a 450 every race fairly easily, & smoke it on top.
If you cannot,,,,,then something is amiss.
Like i said above....you should trump a 450 fairly easily....& that is about it in stock form.
Just abit more noticable power then a 450...............maybe 20% seat of the pants feel.
That is a good running stock K-5.