The DRL system on GM cars can be a bit more complex than what Toyota uses. The Toyota system is pretty easliy hacked. On the "true" GM cars, they have a tendency to heavily integrate the DRL stuff into the body function computer. And it knows when you're trying to screw with it, and will throw up some warning message... I ran across a few articles on this topic when I was digging up info on my folks' 2004 Impala. Seems next to impossible to disable 'em on that thing without some potential issues...BUT, it looks like the GP isn't as bad. I know for a fact it's doable, since I've seen several GP's of that generation running around with no DRL's whatsoever. So, if what the following pages say is true, it may be a pretty easy task to accomplish.
http://www.grandprix.net/faq/http://www ... e.htmlGood luck to ya! I'd say spend a bit of time googling the issue and maybe see what all of the options are for you guys.