I did a new DIY intake tonight. just for kicks. my old one had too much duct tape on it. this one is very similar to an injen intake or the like. It consists of one 90* ABS elbow (the "plack PVC" at home depot) and the tube from a civic short ram intake available at any autozone for 30-ish bucks. IT uses the stock airbox from a 2.2L engine. why, you ask? the stock 2.2L airbox as a very good straight-through flow design, whereas in teh top mount 2.5 airbox the air has to take a 90* turn through a filter. not good for velocity. also, the 2.2L box has a 3" opening on both sides of the filter. I have a small velocity stack going from the box into the fenderwell.
top end is nice, low end isn't appreciably boggy. oddly enough, top gear cruising throttle response is better. like 60 mph in top gear, the response feels better than stock. I'll have pics tomorrow. jsut wanted to mention all this.