I replaced the stock air filter with this:
http://cgi.ebay.com/ebaymotors/WASHA...item588b86d53f
I took a pic but I don't see an option to upload it. I don't have a web site... The air cleaner fits perfectly.
I bought a plastic top from the air cleaner on a junk car for $5. I took the blade off my hacksaw and cut the pipe off. I used a grinder to remove the uneven stuff from the cut end. The air cleaner in the link comes with rubber adapters that "grow" your pipe to 3.5 inches - the standard, for big diesel pickups. So if you can get this (cost was $15 with free shipping) then you can use any clamp-on BUT space is kinda limited and I'm sure a lot of them will not fit, 'cause they're too big.
I bought a strip of soft aluminum at tractor supply, drilled 2 holes in it, made a bend in one end and used one of the old mounting holes to bolt it down. I drilled another hole in the chrome end of the air cleaner, used a bolt, 2 washers, a nut and a wingnut to attach the mount to the air cleaner. Now it doesn't flop around.
here's the pic:
http://thedigitalmage.000a.biz/junk/
The complete cost was $22. Power is up. So is noise, but not to the point of being irritating. Between this and the exhaust, the car is going great!
Oh yeah - there are two rubber hoses that get air from the clean air plenum (inside the airbox, after the filter). I cut some rags and tie-wrapped them around the ends of those hoses, firmly. The larger one seems to feed a vacuum gizmo and I don't want to feed it dirt. The other little one - I dunno where it goes. A rag will remove the dust from what little air they take in.