hi i have a 2001 ram 2500 cummins and i want to run straight pipe stacks is that legal these trucks never had cats on it yet and its a diesel and i want to run twin 5" stacks please let me know or do i have to have at least a muffler on it cause apperently the turbo acts as a muffler too

Newer diesels (mostly after 2007) have emissions controls built into the exhaust but the old ones don't. In my opinion a diesel with a turbo and no muffler is considerably quieter than a diesel vehicle without a turbo and a muffler. That being said you will get a ticket because in Ontario you are required to have a muffler unless you are driving an electric car.

75. (1) Every motor vehicle or motor assisted bicycle shall be equipped with a muffler in good working order and in constant operation to prevent excessive or unusual noise and excessive smoke, and no person shall use a muffler cut-out, straight exhaust, gutted muffler, hollywood muffler, by-pass or similar device upon a motor vehicle or motor assisted bicycle. R.S.O. 1990, c. H.8, s. 75 (1).

so YNOTP you recommend i put a muffler on to avoid any problems? with the stacks?

Putting stacks on a little truck like yours means it's only a matter of time before you get pulled over by MTO or a police officer to see if you have a muffler installed. No muffler means a ticket and there is no defense to the charge as the law is quite clear. So yes, I do recommend that you do have a muffler, better yet drop the stacks idea altogether as you'll be attracting attention to yourself.