This kind of tune is absolutely awful and it needs to stop. Not only is it really obnoxious, it can potentially permanently damage your engine either quickly or slowly.
If you don't know what a "Pop and Bang" tune is, let's quickly dive into what inspired it, how it came about, and where you can commonly find it. On much older race cars throughout the 80s and 90s, you would occasionally see puffs of fire coming out of the exhaust pipe accompanied with a crack whenever a driver shifts up or lifts off the accelerator pedal. In some cases there would be pops and bangs (hence the name) without the fire, which usually was the case with older turbocharged rally cars.
In the case of the former, the usual cause for this was excess fuel that was unburned being sent down the exhaust pipe where it would eventually meet fresh air once it exited - and that usually saw the unburned fuel igniting with a crack. With the latter, it was a result of anti-lag systems that would specifically inject fuel even when the driver was off the gas, igniting it to keep the turbos spooling and to reduce turbo lag.
It made for quite the spectacle, both visually and aurally, and it's understandable that people would eventually try to emulate this for their road cars. But there is a reason you don't really see such systems around anymore and race cars tend to be very clean in their operation - very rarely do you see spurts of fire or hear pops and crackles on the overrun.
In addition to this, that excess fuel turned out to be pretty awful for the longevity of an engine. Of course, race cars regularly had oil changes done after each race outing, and broken turbos could easily be replaced with million-dollar race budgets - as these systems usually did end up breaking a turbo or two on a weekend. These same problems come back to owners who tune their cars specifically with the intent of creating pops and bangs.
Let's explain how it's bad.
Excess fuel thins your oil out
In order to achieve these synthetic pops and bangs, almost every tuner will apply the same principle - dump excess fuel into the engine when you lift off the throttle. The excess fuel does help to cool your engine slightly as it brings heat out with it when the fuel vaporizes on the hot metal, but plenty of the fuel still remains unburned inside the cylinder and mixes with the oil on your cylinder walls.
This oil and petrol mixture then washes down past your piston rings and into the sump, mixing with your oil and thinning it out. The function of oil is partly to carry heat away from critical components in your engine, but the main function is ensuring lubrication in the moving parts of the engine. Having the oil thin out is dangerous as it can lead to increased engine wear, and eventually engines seizing and potentially sending a conrod out the side of your engine block. We have seen it happen before, numerous times.
Exhaust valves can get burned
Some of these pop and bang tunes also have the spark plugs fire as the fuel is leaving the cylinder through the exhaust ports by massively retarding (delaying) the ignition timing. This can result in the burning of your exhaust valves, which can either cause them to no longer seal properly or damage them permanently. Either way, it's not great for your engine.
Turbochargers suffer too
For turbocharged engines, that hot exhaust gas mix enters the turbo at a temperature it really isn't designed for - as even turbochargers have a limit to how much exhaust gas temperature they can take. Excess heat can cause permanent damage through warping of the metal or degradation of the seals, and in more extreme cases where true anti-lag is implemented, the actual turbine fins can get damaged by sheer force of the fuel mix igniting.
There are ways to get around all of this, but you really shouldn't be doing it to begin with - especially as it brings no actual benefit to performance. Pops and bangs are really more for show than anything else - let's be real, there's no actual need for anti-lag on modern, small turbocharged engines as they spool up so quickly as it is. By all means, tune for more power and torque, but causing a commotion with pops and bangs is just plain embarrassing!