just a bring back guys with modded 2 stroke 400,i just got the new FETT brother performance catalog and they sell right now the amazing kick *** air filter for $38,20% more airflow than camparable filters,4 inches long,available from 36 to 46 mm carbs,a REAL power boost,i ran them for 2 years now and they adds more than k&n for sure,warning: take a close look at spark plug colors when first trying them out,enjoy!