Hi, I am new to this forum and I am also new to upgrading car engines. So I was just wondering what kind of upgrade i could get for my 2003 Bonneville SE that I could easily notice a performance improvement. I do not have any other upgrades on my car. The most I would be willing to spend is 300-400$. Just remember that I would prefer it to be cheap.

You could install a FWI About $180
INTENSE-Racing.com: <b><i>INTENSE</b></i>™ Fenderwell Intake Kit for 98-05 Cars
You can also change your PCM, that will change your shift points and make the car perform better. About $100
INTENSE-Racing.com: INTENSE™ Reprogrammed 3800 Powertrain Control Module (PCM)
You can also change your thermo from the stock 195 to a 180 That'* about $10

Thank you for your suggestion. I just have two more questions, first of all for the PCM I have no idea what im supposed to be entering for most of the questions. Also where can I buy a thermostat.

For the PCM, just go with a alacarte, There'* no reason to make other changes. Intense has the thermostats but if your just gettign that, then go to autozone or some other local parts store. Tell them the car you have and that you want a 180* If you just change the thermostat the fans wont come on until it'* over 195* so it wont hold a steady temp. The replaced PCM will change that setting. Now keep in mind you will need to do a case learn with a new PCM. If there'* a local club member that can help you that woudl be great. If not you will need to go to a dealership and it could cost you. You also need to explain to them it'* just a case learn and not a flash. If they do that you loose the tune. Where are you located?

Here'* something else I would highly recomend. It'* not that hard to install as long as you have soem experence working on cars. Takes about 2 hours and really makes the car shift nice.

INTENSE-Racing.com: INTENSE™ Street/Strip Performance Shift Pak®