First of all I am new to this site, so I apologize if this has already been covered.

I have a 2002 S4. It has 56K miles on it and it is APR chipped. Just recently, my Y pipe keeps blowing off under hard acceleration. I found out that the diverter valves were shot, so i replaced both of them today. However, when I went out for the test run, the Y pipe still blew off after hard acceleration.

Could it be the Divert Air Valve Control unit? Any suggestions would be greatly appreciated.

Thank you