Whistling noise when i step on the accelerator

theres a slight whistling noise when i step on the gas (not in neutral, when im in gear - driving). last week you could couldnt notice it unless you knew it was there (friend rode in car and i asked if he heard it and he said he didnt even notice it until i mentioned it) but its getting louder.

heres my car:

hollowed catalytic convertor

i was thinking it might be the hollowed cat… im not sure though

Sounds like you have a pinhole in your exhaust somewhere. It will get bigger and bigger - as it corrodes more and more. Generally pinholes will be found in welds, but if you have an older exhaust, the whole thing could start to be corroding…

i looked under my car and saw that one of the bolts isnt on my cat, guess i didnt tighten it enough so it fell off after a while…

u know how theres 2 that connect to the header and 3 that connect to the catback? i had midas bust off my bolts but i cant get to the top bolt connecting to the catback so i had them leave it off but 1 of the 2 that connect to the header fell off

well that’s your reason why… you’re missing a total of 2 bolts on your cat… Did you put in a new gasket also when you put on the catback? You shouldn’t have ever left of the 3rd on the rear end of the cat, and torque down those exhaust bolts harder!