There is no shop section here, so I am posting here.

My old 1979 K100 Kenworth needs a new muffler.  Just rotted out. 

I am scared to price one. 

Heck.  It is a 10 inch round pipe that is 44 1/2 inches long.  Can't I just make one out of raw steel for $50 or less? 

I was going to take a 5 inch intake pipe, same size as on oud muffler, and run it up about 40 inches inside of the 10 inch pipe with quite a large number of 5/8 or 3/4 inch holes drilled in it.  Cap the top and bottom. Have a pipe going out of the top of the cap to match my "super deluxe chrome" ex. pipe and I am done. 

Right?  Wrong?