Tailspout shape is also really crucial. Rear-discharge greatly aggravates stinkpool. Down-discharge (45° or so, with or without the end of the spout slashed horizontally so its "face" is parallel to the road) is much better. And on wagons, vans, and trucks you want the tailspout to have an outboard angle of 45 to 90 degrees, too; the boxy shape of those vehicles tends to drag exhaust along with it, so you shoot it out sideways to avoid that.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.