Completely without exhaust pipes? 40 minutes! I personally wouldn't dump from the exhaust manifolds.....too much potential for heat and health problems for both you and your truck! I don't want to open a can of worms but I'd be leery of trying it without at least some exhaust pipes to dump under the truck and protect the valves from rapid cooling once you shut down the engine. You could slap on some "Mickey Mouse" hearing protectors and forego the oxygen tank!!!
I ran mine straight back and out behind, under the bumper. If you're going to run glaspaks it may be a bit loud out the side with your window down. I switched over to the CherryBomb Turbos which are much more civilized in that 2300+ range where the paks were just plain offensive. However, this is your personal call. That's the beauty of these old trucks.....you can always make changes to suit your needs.
Dave
