If you want to blow smoke like that on the track, go for it. Don't do it on the highway. It's stupid, lowers fuel mileage, and gets people's attention on the matter.
You can get the new ones to run really clean and not blow smoke even with full deletes.
How much smoke my 90 Cummins blows depends on how smoky I feel like making it when I fuel up. But I usually put a pint of 2-stroke in it when I fill it. A quart is too much, my top speed is about 85, and with a full quart in the tank, I can still blow smoke at 75.
Just think, these early Cummins trucks were "green" before green was "green". The engine is capable of running over a half million miles, they don't require any exotic metals or alloys to make batteries, they get 20+ MPG highway, unless it's got 4.10 gears, and they are simple enough to rebuild any of the components that may fail over the weekend in the driveway.
I figure I could spend 2 years worth of new-truck payments on my heap on upgrades, and unless someone runs into it, I can still be driving it long after obsolete or expensive electronics and emi$$ions parts have taken the new one off the road.