Dyno Cell Help

Looking at building a dyno cell inside my shed.

cell will be 6mx9m roughly 2.4m high.

using hub dyno.

iv read the other dyno cell designs page.

I see about bringing down the outlet to 1m from the floor so help draw air from under car.

Im looking at a 10,000cfm fan to draw air through the rear from the roof.

Inlet air will come from the roof and another fan tompush air through the car for cooling.

my main concern is exhaust noise, I was thinking of running 1 6inch muffler or 2 5inch mufflers with a inline fan on the outlet of 1 muffler to help draw the exhaust gas through and if its to much for one muffler and bypass can go through the other.

Im trying to avoid having a screaming rotary inside the cell and it becomes so loud its hard to hear yourself think.

any sugestions on exhaust noise?

i live out of town neighbours arnt real close but if i need to run a little late I dont want to be limited and keep everyone happy.

Cheers for any input.

if you room , a great dyno muffler , get a 200lit drum , if you can from a chemical company they can have clip off lids , then put tyres in it , it will have the same effect as a silencer for a gun , it will need a serious fan to draw gasses through it