99 4 runner catalytic converter/ exhaust problem?

I have a 99 4 runner SR5 v6 3.4L california spec. I just got my cat changed at a muffler shop but they replaced both of my cats with one which tripped my check engine light. Apparently they probably wont be able to fix it and ill have to take it to toyota dealer and pay $3100 how can i cut the costs. Also how loud would it be if i were to remove the entire exhuast system? and what would be the penalties if I were ticketed for it? thanks99 4 runner catalytic converter/ exhaust problem?let me see if i can phrase this so we can all understand... you know with the help of punctuation and complete sentences.

if you run your car with open pipes it will be very loud! don't know how much your penalty will be.

unfortunately aftermarket cats do not work on toyotas. toyota's O2 sensor parameters are very strict and if they don't see them, the computer thinks that the cats are bad. this happens here at my dealer all the time.

if you just put straight pipes on it, make sure you at least put a muffler so the noise won't be too loud. but your check engine light will stay on until you get toyota cats on there. it should not cause any type of driveability problems.99 4 runner catalytic converter/ exhaust problem?ok first go out to like junk yards ang get two cats instead of the one because they ****** up hard by doing wut they did because with the one cat it will blow out and if u remove ur entire exhaust ull have to put straight pipes on but u cant do that unless the car is 15 years old or older but the car wont pass emissions unless u get both cats back on