This doesn't exactly answer the original poster's question. But since the thread is titled 'which cai' I wanted to weigh in on my recent experience.
I purchased a K&N CAI and couldn't wait to bolt it on..
http://www.knfilters.com/search/product.aspx?Prod=63-9022
Before I even got 1/2 mile out of my driveway I was thoroughly disappointed. It made a loud "plastic" vibration sound under load accelerating (2500-4000k rpm). The vibration was so bad I honestly thought the tube had a crack in it.
I tried to like it for a couple of days, I loosened and readjusted it a few times to try to reduce the horrible vibrations. Nothing worked to reduce the vibration, it is just inherent to the poor design I feel.
Build quality was to Chinese standards imho.
Also noticed mpg went from 17.5 to about 15.9, and not due to lead footing it.
The exhaust note sounds just barely better than a ricer in most ways, it did bring out some growl, but overall I was not happy with it and couldn't wait to put the factory air box back on it.
No noticeable increase in power or performance from the K&N, if your looking for something that 'sounds' faster, you might be happy.
Unfortunately I cannot say enough bad about the K&N. I wouldn't recommend it to anyone. Not the v-8 model for 03 and 04's. Maybe the aluminum tube model would have produced different results? But I think we have very good intake systems from the factory, so it's more of a 'if it ain't broke, don't fix it' kind of thing I think.
Since uninstalling and returning it mpg have settled back to around 17.5 around town. (these are mpg from the computer bear in mind.. well known to be off...not worked out by hand)