Manky Monkey Motors

From where I live, with the windows open because of the warm weather, I can hear the boy racers at the local leisure park & endless sports bike riders, tearing round & round the ring road. When did this pop, pop, pop thing become a trend? It seems to be both cars & bikes, popping & banging like mad as they shut the throttle. It sounds awful, like really bad timing.
What have they done to their motors to produce that effect & more importantly, why?

Blame 'Fast and Furious' and similar.
Race engines have a lot of cam overlap to help cylinder scavenging at high RPM, combine this with excess fuel on throttle lift off and you get popping and banging.
Unfortunately youngsters in their 'tuned' 1.0 Corsa with dustbin exhaust, stretched tyres and a sound system that could soak more power than the engine can produce, seem to think this is a sign of a really fast street car.
Think most of us went through this stage in life but grew out of it by the time we could actually afford to modify a car. Remember 'Carlos Fandango' wheels, fake Cobra side pipes and shaker scoops.

Yeah, I was doing similar stuff to motorcycles, but now I'm old & grumpy & it annoys me!
So what are they actually doing? Increasing the fuel/air mix? Winding up the turbo boost? There's a young lad at work with an Evo which is actually highly tuned. I haven't seen him for a while but hear him arriving & it's suddenly started the popping & banging thing, so he's presumably changed something. Personally I think it sounds horrendous, not impressive. Just sounds like their motors are absolutely knackered.

Spark plug  kit in the exhaust....