I have a friend who used this on his Google ppc campaign and his account is banned. I am reproducing his post from a different forum here: "I am not a fan of this script anymore. This script forces the visitor to click cancel the popup. Unless you do that, you can not click "Back" button which is against Google rules. If you use this on Google PPC campaign landing pages your account will get banned. MR. Dave G knows this. He actually acknowledged it when I sent him an email on this. His response: there are other sources than Google like msn, yahoo... to use. But he won't say that clearly like YOUR GOOGLE ADWORDS ACCOUNT WILL BE BANNED if you use this script. Greedy stupid." Use Exit grabber or Exit predictor Pro instead. Don't blame me for not warning you. I want to post in few other forums also to warn our brothers.
Why not use a software that Gauher Chaudhry recommended called Traffic Regenerator? Its a peel-away script that predicts when someone is about to leave and the peel-away comes up with one last backend offer. Supposedly converts well!
Adwords does not allow any popups, popunders or any separate window that comes up. At any time, even when exiting. It is against TOS and will get you banned if you continue. Enginez has the solution. Have a different page without the popup to send your Adwords traffic to.