Save the money on the CAI and do a Fenderwll Intake instead (70 dollars including the filter). If you plan on modding the car, use a copper based plug (I prefer Autolite and in your case would recommend the 605'* which are 1 step cooler then stock gapped at .055). Also, if you put the 3.4 on I recommend a modular pulley setup such as the one INTENSE sells. Be sure to stick in a 180 T-stat as well.

Your stock cat and exhaust wont be a restriction until you start making more power than a 3.4 is going to give you, however once you start modding the "mod bug" will bite and your going to want to go further (rockers, cam, pcm, etc...) so this may not be a bad idea.

Reliability and streetability is fine with the 3.4 upgrade as long as you do supporting mods (colder plugs, air intake, tstat) and if you want to really spice things up, a shift pak such as the one INTENSE sells set to medium will make it MUCH more fun to drive.