well on my maxx i really diddant have to break it in since i got it from my bro...but when i bought the 4-tec with the 2.5 i new what would happen if i diddant break it in right. so for about the first 3-4 tanks after proper break in i still took it ez as if i was still breaking it in...that could also be tha reason that i have never had any major problems with it....and i Love my little 2.5