For the gearheads in the audience
Well, then it seems like maybe the setback really is too close and you are pushing the cage forward. The only other idea I have is if your penis, when erect, is curved--if it is, it might be trying to push the cage up or down or to the side, but at the same time, getting erect means there's no room for the cage to turn so it pulls. This would especially be true with the Impaler, since the post that runs through the piercing is so long, just a little bit of an angle might cause a problem. The Evotion doesn't seem like it should do that, but I don't know, it seems more intricate, maybe it does. The only way to solve that, I think, would be a larger diameter cage, so it can turn a little bit even when hard. However, that would only work side to side; if your equipment curves up or down, the post through your piercing isn't going to allow for changing the angle up or down no matter how big the cage is. If THAT is your problem, you either have to do a ball-capture device that keeps everything packed down, or maybe a device like MCN has where you can adjust the angle of the post through your piercing, as you might be able to account for the curve and just attach it already pointed more up or down than normal. Actually, that's someone else you can talk to--Mark at MCN. Shoot him an email and ask if he has any ideas. He'd probably modify your Impaler, if he thinks he has a solution, for a reasonable cost, or he might be able to tell you that, if you purchase his Glans Armor, he could do something or other to prevent that. Worth a shot.