New Bosal replacement exhaust makes humming sound

I replaced my 3.4 Taco exhaust last week and now it makes a humming noise when accelerating. It's the loudest at 2k rpm, but it is present throughout any type of acceleration. I read an old post on Ttora about a member who had this same problem, but nothing ever came of the thread. Has anyone experienced this or heard about this with the Bosal replacement. Is this a leak or just how the Bosal exhaust sounds? I could live with it, but just would like to know.

 

Yes, I have a 1999 Tacoma with the 3.4L and I replaced the whole exhaust with a Bosal system. Right from the beginning there was a high pitched hum or a better description would be low whistle which increased, decreased and tone would change with engine revs . This hasn't been a big problem because the truck ran fine. When I installed the system I noticed that the header pipe ( the one where the 2 pipes collect into one down stream before the first O2 sensor) protruded into the two pipes about an 1 1/2", I thought this was odd as this almost looked like a whistle from the inside. I figure if I drumel or die grind this protrusion the noise would go away. Its been a while since your post so I hope you see this and tell me how you made out!

 

I don't think that is what causes the whistle because I didn't buy the whole exhaust system, just the midpipe, muffler, and tail pipe. I don't notice it much anymore. It could of gotten quieter or I just got used to it, but it doesn't really bother me.

 

I have the same noise with a Bosal that I just bought this March. I only replaced the muffler and tailpipe so I suspect the culprit is the muffler. You get used to it, and the performance and quiet seem to be comparable to OE, so I can live with it.