A fully reprogrammed ECU will do wonders on your car (wonders being about 30-40hp for about $1000. The problem with most chipped ECUs (jet, etc...) is that they don't actually tune it directly to your car. If you tune the ECU on a dyno for about 4-5 hours (pretty spendy) it can make a huge difference. The little resistor that the ebay link shows will not do much to your car, and may reduce horsepower depending on the conditions in which you are driving your car. If you are looking for a fully tuned ECU (and you can make it to SoCal) I would check out TechnoSquare
www.technosquareinc.com. The guys down there can do a good ECU reprogramming job...but I won't lie, it won't be cheap.