My car started sounding a little louder.

1)
with the hood open when its reving down you hear a leak and when you shut off the engine you hear pushhhhhhhhhhhhhhhh. So i am guessing its an exhaust leak. am i right?

2)
I did a compression test since i was there and I realized from left to right (facing the car)
210 210 160 205
That can't be good... Any ideas why there is such a huge compression drop? how can i fix it? what does it mean?

3)
While i was doing the compression test i kind if messed up the location of the wires to the spark plugs. I think i got it right since engine doesnt sound like one of the cylcers isn't firing but can someone post a diagram please


Running 1999 Civic Ex 2 Door (Canadian Si) 165,xxxkm