I am looking to get the AEM CAI with the bypass. What I want to know is how do I find out what size bypass to get?

 

You should get the 2.75" one. Part# 20-402. Check out this link for more applications.
http://www.lightningmotorsports.com/index1.htm

 

From what I hear their pretty useless you plan on going through like 2 feet of water and by that time you better be more worried about the water coming in your doors.

I've had my AEM for a long time and I've gone through some pretty crazy rains and I've had no problems.

 

That is true. But I rather be safe than sorry. I also live in Flordia and we get a sh*t load of rain in the summer.