I recently installed my downpipe with a wideband and got it tuned at TopSpeed =]

but I just started to hear this rattling sound, its not knocking. its more like something is hitting again something; like metal to metal. I can't pin point the source, but I think its coming from underneath my car, like the downpipe. I am sure I installed everything right and made sure everything was tight.

anyone have a similar problem? think it came loose again?

 

and one more question. I have a VDO boost gauge and it works fine, but when I just checked, the gauge line was collapsed* (edit)

should I get it replaced?