can (2) 1.5" exhaust flow into (1) 2" pipe?

[1816case]

Putting some kind of exhaust on my mitey mac 8b. it has the Onan engine. Currently only has the exhaust flanges on the engine with maybe 3" sticking up.. I bought some 1.5" exhaust piping and am wondering can I run the 2 exhaust tubes each up and into a single pipe of same 1.5" or maybe a 2" tube and run that single tube back to a muffler say off a tractor ..? will that restrict flow?

 

[foton]

1-1/2 inch should be more than plenty,I would design the exaust around the type muffler that you are going to use,this thing is going to be right behind your head so I would work on a quite as possible muffler. And watch your exausts weight on those flanges further support might be needed , dont want to bust those with excess vibration either. Of course you could use one muffler per cylinder ,cool dual exaust on a skid steer.