vibration different in sms

So, like it seems for many of you, I don't like the loudness and duration of the vibration of the iphone 5/5S. I have made a custom vibration for everything on the phone. Just the lightest little bump on the screen to get the tiniest vibration. My only issue is that when I am engaged in an text conversation with someone, by custom vibration does not work if the Messages app is opened and running. If the phone is locked, or unlocked on the home screen, I get my nice, quiet, peaceful vibration. If i am actively engaged in a conversation with someone via text messaging, it sounds like someone is revving up for a RC drag race. Is there a way to force the custom vibration while the message app is open?