Well I put on a round air filter a few days ago . But now I have a bad hissing noise when the motor is not warmed up and when I get on it . Any one eles ran into this?

 

You will heremore sucking than you usedto, it's the nature of the beast. If you feel like it's too much though, here are afew things to check:

1. Check that the AC is seated on the throttle body flushly and that the filter is snug in theAC housing.
2. replace the AC gasket on top of the throttle body.
3. Check the vacuum tube hose that goes into the throttle body in the front under the AC, mine was cracked and it whistled loudly at WOT. it's just a small rubber tube, not any special part.
4. you might also try to run a bead of grease around the rubber "gaskets" on the air filter inside the AC housing.