whistling/whining noise

Okay so yesterday i took my valve cover and timing belt cover off and everything else you need to to get those two peices off and checked my t belt and adjusted the valve clearance to stop the ticking. And when i put it all back together there's this whining/whistling noise and i can't find any vacuum leaks or anything like that it progressively gets louder the higher the rpm but I've seen no performance loss so far. The only thing that has changed is that aluminum tube thing that goes between the air cleaner and the exhaust manifold is gone cause it was falling apart anyway could that be my problem u think? Like air sucking into the air cleaner or somethin i just don't wanna get down the road and have some shit break and be stranded. As always thanks for the input.

Just a quick add to this any1 think it could be the t-belt? It kindof sounds like a blower style Supercharger type whine and i did remove the t-belt cover. Thanks as always.

Something rubbing on your timing belt?
Get your head under the hood and see if you can hear exactly where it's coming from.
Feel for it if it's coming from the timing belt
Got one of dem clever phones? Take a movie

I don't know but im gonna pull the t-belt cover off my next day off and see what's what. Quick dumb question: does the gasket on the cover serve any purpose? Cause mines all torn up. Its the one between the upper and lower covers and i got to thinking that i may not have peeled it all off and maybe its wedged between the two rubbing on the timing belt. And one further q if the t belt were to break would my valves get messed up or no im sorry i know this is gonna make me look like a total dumbass but im used to working on old domestics not foreigns and i know i had a neon snap one at highway speeds and destroyed the valves. So thanks as )

The gasket stops crap getting in, mostly dust.
It's nice to have it clean in there, less wear etc.

It's a non-interference engine, so less likely to bust valves if all goes wrong.
(in theory it shouldn't bust any, highest point of piston < lowest point of valve = non-interference engine)

Most interference engines have a chain, not all though

(Actually, someone cite me!!!!! That's too important for just one mans opinion! lol)

Thanks Jenko i thought that it was a non interference motor but i didn't know for sure i will try and find a new gasket but for now im not too awfully worried about it and i do plan to change the belt within the next few months cause i just bought the truck and i don't know when it was changed last! But as always thanks and ill keep everyone posted.

One more quick note: any1 know where i can find one of those lil rubber gasket things around the valve cover bolts? Any help would be appreciated. Thanks as always.

Buy a felpro valve cover gasket kit.I know auto zone sells 2 versions.One with the grommets for the bolts and the other with out the grommets.I could dig out the part # but wayyyy to lazy and you can go chk it on there site they do normally stock this item with the grommets!As for the dust seals a mazda item and I replaced mine back in 2010.And is for the timing cover plastic pieces upper and lower.Idk if anyone else sells those dust seals but mazda carries them.

Thanks 87 forever i guess i got to take a trip to the parts store! I appreciate everyone's replys and will let y'all know what's what this weekend when im not @ work.

Okay so on that t-belt how tight should it feel like tension wise because mine has some play in it and i don't know if it should. When i pulled the upper cover off i kindof had to pry it out so is there any way i may have messed with the tensioner? I don't mean to be so noob sounding i really do know a bit about mechanics i just don't know these motors at all. As always thanks guys