The way I did it-buy a motorsaver airfilter.

http://www.amainhobbies.com/product_...oducts_id/3171

Now take the filter neck off of both filters (stock and motor saver)

Take the stock filter neck and trace the outline of the big end onto the motorsaver where it would connect to the filter neck. Then sketch a circle inside of that, about 1/4" smaller.

Cut the MS filter housing on the smaller circle. Try to put it onto the stock filter neck. If it doesn't fit right, make the hole larger (should be too small right now) until it fits almost perfectly. Now seal the two peices together with shoe goo and it works great.




But there might be one out now that comes like that, haven't looked recently.