Hi am looking for some performance parts to give a kodiak I'm getting in a couple days a little more power and speed to keep up with a friends 400ex that is currently stock but getting dual big gun EVO x's soon.Now I know the ex is a lot faster but I am just trying to keep up so I decided on K&N air and oil filters and a stage 1 Dyno jet kit that I'm sure i'll need with the k&n and new exhaust.I am looking for an affordable slip on and came across the DG that I found for $150.Is it any good or just a waste of money I am not looking for an hmf because the price is too high for the slight power increase of a slip on. I am also looking for a performance spark plug but I'm not sure if any are made for the 400.And if there are any other small modifications I can do to it please tell me just no engine work.Thanks!