Annoying resonance on newly rebuilt 2.4

[Deschodt]

Title says it all, well almost... This is a 2.4T engine, that just got rebuilt... Currently the MFI pump is resisting perfect adjustment (sat on a shelf too long) but it runs well enough to put a few break-in miles on it. The exhaust and headers were so rusty that we replaced them with a stock new muffler and SSI headers... I'm wondering if that was a mistake ?

At 2800 rpm windows down the resonance is annoying, it is loud and not a good kind a loud, booming loud... Also, at idle - only when fully warm - 210 or so, there is a pulse that feels like a wave of air hitting my ears, it's actually almost painful...

The engine runs well, considering the fuel distributor is not on the money yet, and it's has not yet been retorqued, retimed, rechecked like you do after 1000 miles on a new motor... Do you guys think that a) there's something wrong there b) it might get better after the initial retorque, it's brand new after all c) that's what you get for using an SSI...d) all of the above ?

Thanks !

[tobluforu]

If this is a stock muffler then there should not be any drone, etc. Adding ssi's is pretty much the same as having the stock HE's, performance wise and sound. I didn't notice any increase in sound when I went to SSI's. Do you have the sound pad installed, carpet and all sound deadening still in the car? Now, from what I have read after some miles are put on it that the muffler will quiet down some due to carbon or whatever. I have had numerous mufflers on my 72 and the stock muffler is damn quiet, "to me."

[RSTarga]

I have the same setup SSI's + stock 2 in 1 out. Are you running the stock air cleaner? Are your throttle bodies good and setup correctly, linkages etc.?
Without air filter their is a resonance from the intake.
I only had resonance from the exhaust when I used a 2 out sport muffler.