My 2.0 jetta seems slower than it should be. Does unplugging my O2 sensor for the stock intake affect my performance? (i had to unplug it to put in my HP intake) Also what else can i do? my budget isn't great, but maybe theres some tuning i can do? also, would putting in racing spark plugs optimize performance? if so which should i buy? thanks for w/e you guys can do.

- Lou  

your 02 sensor is in your exaust and should not have to unplug it for a cai...soooo i assume your talking about a mass air sensor and yes a mass air will greatly affect your cars performance.  

There are ways to tune it with the mass air flow still in its cavity. Any spark plug you get will give you a more efficient burn but if you haven't got it tuned electronically, it's pointless.  I don't know V-Dubs that well but I assume that the same principle applies when tuning one. Maybe you have bypass in the rings or maybe the valves and injection system is dirty. Try giving it some maintenance before you ruin some thing in the PCM. V-Dubs are sensitive. Don't mess with the electronics unless you are well versed in its functions.
Wow, I replied to a thread written in July of this year. Oh well...