Odd noise at 5000 RPM

[InCoGNiTo]

well, decided to give the car a little run today and I discovered some funky noise at approx 5000 rpm.
The car is still 100% stock with the exception of no cat converter.
At WOT and getting close to 5000 rpm theres a slight vibration and then the noise, the best I can decribe the noise is its something like 4 barrels opening, normal talon noise to "whoooaappp" (forgive the expression)
4 barrels, deep throaty noise, "intake on civic noise", its very noticable and very loud and its right around the 5000 rpm range and on. I rarely take my car up that high, but when ever I did, I never heard that noise. up untill today anyways.
Theres not alot of vibration, but enough you can feel it in the steering wheel and in the shifter. up untill the noise starts the car feels normal.
it seems to have the same amount of power it always did, but does not sound the same, ovisouly. Idle is fine (slight fluxuation on the stock tachometer but slight enough so you can barely notice it on the dail).
boost and vacuum seem normal, normal to where they always were for the past 6 months.
So far i've checked small things, boost tubes, hose clamps,air filter, intercooler and so on, all that seems fine.
it seems to be an intake related problem to me but i could be wrong, so I started off by checking the simple things regarding that.

I don't know what else I can add ? that seems to be what its doing.
any suggestions to solve this problem, something must be wrong, cause it never sounded like this before.

any other info just let me know and ill to my best to explain it.
any help or suggestions would be great.

Thanks

 

[InCoGNiTo]

Anyone ? suggestions/comments ?

 

[dartgts]

Well kinda funny you are having this problem.. I just fixed it myself. There were (2) things wrong one I found to late the other I found by accident.

1) the balance shaft belt jumped timing (if you haven't taken it out yet). This also led to my demise.. It broke and wrapped around the timing belt bent all 8 intake valves and one exhaust valve.

2) Cracked exhaust manifold both under and the fins inside. I would check these because what you describe is exactly what I just fixed...