this is a total hypothetical. would it be possible to run a "y" pipe, to run a regular old fashioned exaust, then pull off a cap, and run a stack when you choose?
my seem like an odd question, but when im out with a client, a smoke show behind his window may seem less inviting, but then having the option when a person wants.
anyways, just an idea

 

call and talk to wally at FTE diesel I dont know what is up with his web site its having major worms. but the number is good and he can tell you pending what you want chrome not chrome etc. etc. size and shipping

 

actually someone through wally at FTE used his products and made this with a actuating electric butterfly style valve closed was used for stack open closed stack and used for a short dump exhaust underneath. I think I saw it on cummins forum maybe. I have seen it before someone taking 2 90 elbows and fabbing the valve in those.