Diy K&n Cai?
 

I was in Advance auto the other day and saw a cone K&N sitting on the shelf and started thinking is there a way I could clamp one on to where the stock air box sits? they had a 3" and a 4" and I almost bought the 4" thinking it would work, but I wasn't sure so I figured I would consult the forum and see if anyone could help. Ne one have a part number or size for the filter? ne help with this one would be greatly appreciated.

You don't want to run a K&N air filter, but lots of folks use other, better, filters with custom setups.

Based on what I have seen on the dyno the 3rd gen OE intake is pretty good, and supports at least 450 rwhp, and the aftermarket ones offer no gains up to that point.

If you do want to spend some money on your intake and are under 450 rwhp I strongly suggest:

Good filter, OEM 4" pleat or Amsoil are hard to beat for filtration, OEM has more flow.
Airaid MIT (eliminates the baffles, and smooths the air before the lower elbow)
04.5-07 lower 90 elbow w/ vanes, said to make the turbo up to 30% more efficient.
Intake Horn, GDP is what I run, had to be the cost:performance.
Home Depot CAI

Those mods will decrease your IAT's, increase turbo response, and flow more air than stock.

I'd click here and then click on the Willy's Whistler. I'm building one with a 4" instead of a 6" because I didn't want it too loud