I have mentioned in another thread that I have this exhaust resonance between 1200-1500 RPM. I saw an article in Popular science last year where an engineer was assigned to try and rid the exhaust of this problem. I've seen in other posts here that the 2005 should have less resonance than the 2003 and 2004s. I have ordered a new catback for my truck because of this annoying noise and the fact that Mofo was offering such a good deal. I will let you know how the new exhaust sounds when I get it in.