So I m going to be picking up an air raid siren which weighs around 300 pounds and its going in a Toyota Sienna. Is that too much weight??

That's like the weight of a normal American adult, so it should be fine ;)

HI so you will need to put it on the back seat.

A fat man in the trunk. Do you really think that would be a problem?

300 pounds is like two average weighing people. So how does your car perform when you have two passengers in it? It shouldn't make a difference with the air raid siren, as long as you don't have passengers in your car at the same time.

No.

Try to put it close to the middle so the weight rests on all 4 wheels, but really it weighs less than 2 adults. If you think your Toyota could carry 2 passengers you should be OK

I would say no.

Are you planning on using the siren while you are in the car with it? You might want to rethink that and reevaluate your need for future hearing.

no.

No, but Fat Mary will have to stay home after that.

sounds like it