does aluminum airbox really increase that much airflow and max hp, ive been reading on them some tonight, and most of em are sayin to rejet the carbs for max effect, and if they are all that great whats the best filter to run, i know if you sand ride alot the factory foam ones are the best because the k and n's allow too much tiny particles to bypass, and by running a prefilter that just pretty much excedes its purpose, I think, anyways give me some advice

the aluminum airboxes do not have lids, therfor you will get a-lot more air to the motor, requiring jetting changes. many of the aftermarket boxes use the same filter as the 250R. I've always run a k/n with a water repelant outerware and have not had any problems. the outerware may block a little air, but your still getting much more than you would with a lid. save the cash and remove the lid on your stock airbox, put a godd filter in and rejet. if you have a yamaha, bolt the filter flange to the airbox to prevent dirt from getting by it. if you have a predator, your just screwed, you need an aftermarket box because of the shitty one it comes with, if thats the case cfm makes a nice one.

rather than spend the extry money on an aluminum airbox you would be better off getting a filter kit like a pro design or whatever it is. Then depending on the quad you have get a less restrictive airboot to facilitate airflow. The YFZ's and z400s have crappy airboots that choke the air. You can make a 400ex airboot work on the z400 and possibly the YFZ but I dont know about other models of quads. I run K&Ns in the sand and used them on all my MX quads with an outerwear and never had any issues. The only builder I know of that is a major proponent of the foam filter is Curtis Sparks, whist other builders like Packard and Muchmore recommend K&N.
isaac

by the way i have a z 400, ive got nothin against k an n, ive just been listening to a couple of mechanics who work for a honda dealership, im pretty content on getting a aluminum airbox i was wondering who makes one of the cheapest

Im missing your point on why you dont just take the lid off the stock airbox and save yourself some money??? Oh well I guess you just cant tell some people anything. Spend on, spend away!!!!!!