Stacks are awesome, but I understand blowing it in the window too.
When I first put the 6.5 back on the road after tuning her up, i was amazed by the amount of smoke to be had by putting it in overdrive at 35 mph.
We have school zone in which you are to slow down to 30KMH (20MPH)
I like punishing those who speed in them... ):h First car was a dude in a Mustang GT that tried to hook up to my bumper. lost his headlights in the smoke, and then saw he was a couple hundred feet back.
here's a few more
One was a construction zone that went from two to one lanes. looked in my mirror and there is a guy on a scooter trying to get in front of me. he could have literally put his hand out a little and touched my rear fender flare. so i sped up, and kept him behind. as soon as we cleared the zone, into 4th and floored it. i saw his head catch the smoke perfectly in the face and he started swerving. made it to the curb and stopped.
the second was in traffic. i am changing lanes. shoulder checked, and start to come over. here screaming and swearing and a little horn going off. get back into my lane and some hippy college dude on a scooter, (again), pulls level with me screaming and swearing and giving me the bird. i tried to to apoligize but he keeps going. he pins it and slowly pulls ahead. i am watching him as he is whipping in and out of little spots in traffic and realize i didn't see him because of the way he is driving. figured he was going to one of the local college campus', so i follow him for a while, and sure enough, he pulls off on a nice long turn lane. i get in front of him, slow to 50, and spent about the next 30 seconds layering the road nice and black,

before pulling out in traffic. made my day as he had to drive in the cloud.
dang scooters.